For MSFs I actually prefer my 182. It's more dense than the 150 and buffs everything in soooo well. I do not own a MAC150, but I do own two Sigma SS150s and I love them both. (I find they're actually softer than the MAC 150s I've felt). I use the 150 for dusting transparent finishing powders, to set my makeup etc.
The 134 was the only brush I ever returned to MAC...go figure.