Acastina, I agree totally with your comments. The "gateway drug" argument is a strong one in our culture. It tries to explain our innate "slippery-slope" fears for exactly the reasons you pointed out. Namely the largely western societal need to fit things into the binary. A moving target is scary and can't be controlled. Things are either good or they are bad. With us or against us.
I'd like to add a further bit of exploration of the topic also by way of metaphor. To me the OP question is very close to the "is there life after death" question. How could someone really know if they would be happy on the other side? Not by speculation and imagination. Or even acting it out. Yes we (or perhaps some of us) do feel that we are of female gender inside. But to say conclusively is impossible until you've taken the irreversible step of SRS.
I'll also add, at the risk of offending - and that's not my intent, that I detect a small but persistent undercurrent of regret when reading many of the TS posts on the overall forum. That feeling I get confirms to me that it is not a forgone conclusion at least in my head that the path leading from CD to TS is a one way street. The many poster's voicing the argument that this world we inhabit whether TS, TG or CD is a continuum is correct in my opinion.
LB