Exactly! Coalitional terminology can be very powerful in building cohesive movements and cross-boundary solidarity, but can serve as a bit of a double-edged sword and lead to a glossing over (or even erasure) of the rich cultural differentiation within (Julia Serrano talks a bit about this in Excluded: Making Feminist and Queer Movements More Inclusive, and Viviane K. Namaste's Invisible Lives: The Erasure of Transsexual and Transgendered People has some really great insights about this, and addresses--in a Canadian context--the way that the dominant trans discourse in Canada is english and thus Canadian legislative and organizational initiatives often reinforce an english framework of transgender that seeks to supplant french transsexualité)

Editing to add: if I'm remembering correctly, Leslie Feinberg's Trans Liberation: Beyond Pink or Blue talks very specifically about the difficulties in forming those coalitional ties in American organizing between trans people and gay people, and the struggle to get gender minorities and sexual minorities to see their oppression and liberation as intrinsically linked.