That's probably something you have to answer for yourself. People generally don't like the same things, some people like Pro RMK's while others like ski-doo xm's - both handle very different from each other.
For me, the 12.5 ST with TSS will work much better than the SX-LT, I'd even choose the ST without TSS over the SX-LT. I just don't care for the feel of the longer track.
I agree with this as well, everyone likes different setups. I'm with you here, I prefer the shorter setup even though it won't float as well.