You're right that a great deal hasn't changed in the last 100+ years. And yet, a great deal also has changed, from dominant miasms to psychological and physiological understanding -- and also the disease pictures some patients present in response to social and cultural changes.
I spent my first year of homeopathy school at ICH, so I know it first hand, and also have kept in touch with my classmates. In general, even people who have completed the four years of the complete program (a very small percentage of those who start -- most drop out, and a few switch schools, as I did) find it a bit hard to build and maintain a thriving practice. They're in the situation of trying to cope with the 21st century's problems using only 18th and 19th century tools.
For one thing, their attitude is that the patient should know nothing about the remedy or its reasons. They use only dry centesimal potencies, for all situations. They never repeat a remedy before several months have elapsed. When a patient is miserable after taking a remedy, they say that it's a "healing crisis" and the person just has to wait until it's over (which can be months). They insist in all circumstances that a patient must avoid coffee, alcohol, sugar, late hours (that whole litany of "thou shalt nots" that is listed in Chronic Disease!). The patients I've known who have consulted with this group of homeopaths have had a very high drop-out rate from homeopathic treatment -- they have found the treatment difficult, with unclear results and little nurturing. Perhaps other patients find this approach really suits them -- I have no way of knowing.
The school's graduates are unacquainted with any of the more recently proven remedies (in the last 100 years). They are unacquainted with any of the recent work on classifying remedies and identifying miasms beyond the initial three to help make prescriptions more accurate. They refuse to treat a lot of patients -- anyone with a serious disease, for instance, or anyone who has a long psoric history. They rely heavily on repertorization for finding prescriptions, and some of the helpful newer ideas that rely first on finding the "core delusion" of a remedy or combining physical and mental/ emotional themes (rather than discrete symptoms) are unavailable to them. They are also not likely to think creatively or daringly in solving a case.
On the positive side, they have an excellent knowledge of the Organon and of Kent's Repertory (later repertories are considered "unreliable" and "non-classical"), and have studied homeopathic philosophy in depth.
They are also not likely to be side-tracked by allopathic thinking! (Unfortunately they've also been taught that all allopaths are essentially villains, and there is a lot of hatred behind that attitude. I was essentially excommunicated from the school when I started seeing a potential life partner who was also an allopathic physician. I was called aside and warned in a private interview that I couldn't do that and still be a homeopath! I kept the relationship, switched schools, and still became a homeopath.)
Back to the positive, they have devoted a lot of energy to learning homeopathy, and are intensely dedicated to preserving the purity of what they've learned. They add to the breadth of our homeopathic spectrum, and in the process enhance the quality of our day to day dialogue on homeopathic issues.
Are the changes imposed by a century significant or trivial? Obviously, I've concluded they're significant, and in my own practice, I find that resources from modern experts enhance a majority of my work with patients -- but I also really appreciate and am grateful for having had a thorough grounding in the basics of homeopathy through my time at ICH. As usual, no one side has all the answers.
) Rosemary