Agree @MaryAnn, hence the first point I made:
the main question would be: will we be able to get many members involved in filling in a survey or other form of data collection (including those that once reached maintenance but are no longer active in the forum)? On your second point: from a standard 'medical research' point of view you are right. The trouble is: who is measuring hormone levels, TDEE and such over a period of 3 years or more? Since nobody seems to be able to pull off such research, certainly not with a larger number of real persons (as compared to mice), we might look for different research designs, especially if we think psychological, motivational and behavioural factors also play a major role in maintenance.
Again, I agree with your points basically, but I'm also very frustrated by the fact that the medical perspective on weight and health issues seems to result in very carefully designed medical studies only, where very specific groups of respondents are studied in small numbers over a very limited period of time, using very specific 'interventions'. We need more information on what happens to many different people in real life conditions over longer periods of time.
As you might guess: I have a social science background