I think the two sets of terms developed in isolation on different boards, and now that the populations of those boards are mingling, the terminology is shifting. (The 21s century version of major world languages shifting in accordance with human migration patterns.)
Personally, I prefer TS1 and TS2, partly because they have that cool movie-ish look, like a Mission Impossible title, and partly because I'm tempted to mentally pronounced FNIT and SNIT as if they were just capitalized words, and snit actually IS a word, and one that does not fnit -- I mean, fit the mood of the scene.
But let's see what the majority of us prefer!