I thought I'd share some recent experiences with the other TSM owners (or prospective owners) out there.
I finally got around to using a simple bubble level to align my speakers relative to the floor, as the manual suggests. The improvement that resulted is amazing! Tonal balance is improved, but even more, the spatial presentation is better than ever: the speakers "disappear" more than ever before, soundstage width and depth are much greater, and there's an even more coherent, seamless quality than i used to get... which is really saying something.
I wouldn't say the TSM's are fussy about placement, per se, but they do give you clear feedback on even small changes, making taking the time to make adjustments really worth the effort. Just when you think they can't sound any better with your current equipment, you try a small tweak, and they surprise you!