There are two figures in the history of ideas that Ken Wilber reminds me of (from my superficial reading of these subjects). The first is Pico della Mirandola, the Renaissance Platonist and Humanist. Note that in those days "Humanism" was not at a secular reaction against religion, but focussed on the relation of the human to the divine, seeing in human beings the summit and purpose of God's creation. The second is H.P. Blavatsky, founder of the Theosophical Society, who single-handedly created modern western esotericism.
Just as Pico attempted to establish a universal religion and system of knowledge based on a synthesis of Christianity, Platonism, Aristotelianism, Averroism, Stoicism, Hebrew thought, Jewish Kabbala, and many other fields of knowledge, all incorporated into a single all-embracing religious and philosophical system, and publishing his 900 theses on all possible subjects, "Conclusiones philosophicae, cabalasticae et theologicae", so Wilber seeks to incorporate all current fields of human knowledge within the compass of a single "Integral" philosophy.
However, the "neo-Renaissance" Wilber also differs from the Pico and his contemporaries in at two important respects. First, the Renaissance scholars were romantics, a philosophical position that Wilber rejects as "pre-rational". The Wilberian approach to systematising and categorising is ironically much closer to the Aristotelian and Aquinian position. In fact he goes further and rejects metaphysics altogether, so his sympathies are with the nominalist polarity of secular modernity. Second, as Richard Hooker observes "Renaissance Platonism cannot really be easily considered as a school or even a coherent movement, and apart from the Academy founded by Marcilio Ficino and Cosimo de'Medici, it had very little support as a distinct discipline.. It was more important for its diffusion into a variety of philosophies and cultural activities, such as literature, painting, and music." [ Renaissance Neo-Platonism] In contrast Wilber has established a school, an institute, the Integral Institute, based on and around his own systematisation of all human knowledge.
For this reason, a better analogy to Wilber's revolutionary approach and synthesis, although perhaps one he and his students may feel less comfortable with, is Madame Blavatsky, perhaps the greatest esoteric-exoteric synthesiser of the 19th century (Hegel of course was superior in philosophical systematisation, but Hegel did not deal with mysticism and esotericism). She also in 1875 (with the help of Henry Steel Olcott and William Q. Judge founded an institute - the Theosophical Society - "to collect and diffuse a knowledge of the laws which govern the Universe". What is interesting Blavatsky was the first to incorporate East and West in a way that gives primary emphasis and praise to the wisdom of the East. Many concepts that Wilber presents in his integral philosophy - the stratified reality with its manifold levels, the long, painstaking linear evolution of the self through all these stages to perfection in godhead, the monistic emphasis on the impersonal Absolute (Atman-Brahman) as the ground of all, the vedantic koshas and the trilogy of gross, subtle and causal states, the sympathy to and development of Tibetan Buddhist teachings, the harmony between and synthesis of science, philosophy, and mysticism..., all these and more are common to both the Theosophy of Blavatsky and her successors, and the Integral Philosophy of Wilber and his students.
This is not to deny that there aren't many differences as well. One of the most obvious is the rejection of occultism. Wilber follows the western reductionistic psychology of Freud and his successors in reducing occultism to infantile wish-fulment. He does acknowledge the siddhis and powers of advanced yogis, but only because this is part the entire Eastern tradition of spirituality that Wilber upholds.
In the last quarter of the 19th century, and the first third of the twentieth, Theosophy was a powerful and widespread movement. But Theosophy failed because of it's reliance on psychism, even more because there was no one to take the place of HPB (as Madame Blavatsky was affectionately known). Blavatsky's appointed successor to head the Theosophical Society, Annie Besant, the famous feminist and polemical writer, had a well developed intellect but lacked gnosis and clairvoyance. She thus began to reply heavily on the ex-spiritualist Leadbeater, who brought his own ideas into the movement, intermingling them with Blavatsky's own, and this "Neotheosophy" (as it is called by those outside the Adyar movement) resulted in a split between the original Adyar Branch and Blavatsky purists like the Point Loma group. Even worse was Leadbeater's obsession with finding a world teacher (compare here Ken's feelings about Adi Da), which led to his discovery in 1909 of the young Krishnamurti, who he claimed was to be the body of the World Teacher, the Christ. The Order of the Star in the East was founded in 1911, to great fanfare, but after some years the now more mature Krishnamurti could not tolerate the adulation and expectation heaped upon him, and in 1929 he dissolved the Order, renounced all claims, and repudiated all religious sects and organisations. The "Star of the East" debacle was a PR disaster for the Theosophical Society, and marked the end of that movement as a respectable and active force for social transformation.
I would suggest here that Ken Wilber, as the charismatic powerhouse and sole theoretician of integral philosophy and the Integral Institute (along with its offspring, Integral Naked and the Integral University), has a role in the early 21st century is very like H.P. Blavatsky had as head and almost sole theoretician of the Theosophical Society in the late 19th ( Subba Row also provided some material, but in no way comparable in originality or prolificness). In both cases we have an influx of eastern wisdom, which is reconciled with the science and knowledge of the West. In both cases we have the creation of an entire new way of seeing things, incorporating all human knowledge into a single magnificent and immensely elaborate edifice. In both cases we have an extraordinary, brilliant, and charismatic teacher who is the powerhouse behind the entire movement. In both cases the movement develops rapidly, revolutionising the alternative movement or new paradigm thinkers of the day, who then and now are seeking a viable alternative to dogmatic literalist religionism and reductionistic scientism. And in both cases the new movement and its founder have both bitter critics and loyal and enthusiastic disciples.
In short, I suggest that Wilber's Integral movement is like the Theosophical Society when it first began, full of light and significance. And this brings us to a note of caution. For all such movements collapse, or degenerate into fundamentalism and misinterpretation, when the founder departs, or becomes an empty shell, going on the momentum of past glories. It happened with Theosophy, with Christianity, and it can happen with the Integral movement. The integral movements greatest strength is also their greatest weakness. Without Wilber's genius and inspiration, they will become just one more footnote in the history of the lead up to the New Civilization. Just as there was no-one who could replace Blavatsky, so there is no one who can replace Wilber. The writing is on the wall.
I believe it is important that the Integral community go beyond its current Wilber-only memeset and become a true integral movement, embracing all the thinkers for a new world and a new visioning, then it may yet become something great. Unfortunately, movements like Theosophy, Integralism, and others tend to based on self-perpetuating thought-forms; as with the Catholic Church and (perhaps to not so great an extent) Normal Paradigm Science it becomes very very difficult to introduce new memes, especially if these memes lie outside the teaching of the Founder and/or the main authorities in that institution.