I had not myself. But this is likely because with MAG-10 and Methoxy-7, I’m directly involved with the projects, but Myostat (and many other Biotest products) I am not, since others developed them. (Hey, I can’t come up with every good idea! 
I think you have an interesting idea. I see the situation as being similar to a hyothetical that I considered a number of years ago. Specifically, a given supplement had received a lot of hype and did have scientific evidence which did suggest that it might be an excellent supplement for enhancing lean body mass by, so to speak, tipping the anabolic/catabolic ratio a little bit, which could perhaps over time accrue to something quite significant. However, when released to the market, no one got rapid gains off of the product, and so it was quickly deemed a rip-off.
It seemed to me that if a product gave a user
say 10 pounds more muscle over the course of a training year than he would obtain with it, for an advanced trainer this is an excellent product if not too expensive, yet its rate of results would likely be too subtle for it to appear to be doing anything at all within the first couple of months, and so deemed worthless. So it could have been that the product in question might really have been a good one of this sort, or of course it could be that it really did nothing.
A scientific study done in a more ordinary manner to resolve that would be virtually impractical to do for various reasons.
However, I thought that one could get good results in another manner by (I had then thought) having the program directed by say a professor of exercise science and run by grad students, and simply allowing a very large
number of subjects to either receive the substance or placebo, acquire before and after bodycomp results one year apart, screen them for not using drugs (interview and with signing a release that they may be urine-tested, you never actually bother to do so however) and allow them to train and diet
as they wish. You’d need several hundred per group.
However, with further experience in academia I recognize it would be almost impossible to get that done in that way.
The way you give above, that does not have
placebo groups, I am not so sure of. In the first group you give, I’d already known from experience that anabolic steroid users are typically not accurate in estimating what sort of gains are realistic for them to achieve in a given cycle. They almost always overestimate, sometimes to a degree that’s silly. Some MAG-10 Challenge entrants really exemplified that, for example. I mean, guys that had been using steroids for 10 years, had done cycles of as high as 2 grams per week, and then when asked how much LBM they’d expect to gain from 500 mg/week over 8 weeks, they give a figure that’s 10 pounds more muscular than they’ve ever achieved before! I’m not kidding.
So, if Myostat gave for example five pounds
more muscle in three months, which I’d consider an excellent performance, I don’t think the anabolic steroid users would individually be sure there was any effect at all. Similarly, if it gave no results, many might feel that it did, because for reasons having nothing to do with Myostat their cycle went really well, and they did not happen to be over-estimators beforehand, as some are not.
There would also be no way to look at the group numbers and say, well, you wouldn’t expect these guys to have done this well on average without the Myostat, so the Myostat must have worked – or vice-versa – because one just doesn’t have the basis.
The third group, again, I don’t think you could tell anything. If they got 5 lb more
over 3 months than they “would have” with
placebo, there’s no way to know whether that’s
the case or not. They themselves, at this point, can’t estimate what they might do in 3 months. Perhaps nothing, perhaps 5 pounds or more without taking anything. They just can’t say.
The second group (experienced trainers),
could be.
I’m not personally involved with Myostat, unlike MAG-10 or Methoxy-7, and so I cannot say at all or do anything either, but I’m sure those that are involved with Myostat and can do something here will read your post! In the meantime, Myostat has been out a while… and the judgments of say 100 people who bought the stuff and used it has to be equally valid as a lesser number that are given it free. So I will start a new thread asking for all opinions of experienced trainers who have used Myostat for at least three months, and anyone who has used for 6 months most definitely please respond; and please respond whether opinion is favorable or unfavorable. That should quickly answer the same question, really!