The H/Ks are pretty sweet as you can seperate the crossover range per speaker set (i.e. - 100 Hz for center, 60 Hz for front, 80 Hz surrounds). I have my front speakers set at 60 Hz as I felt the M60s could handle the 60-80 Hz range. But if your receiver does set Hz ranges for all speakers only, 80 is usually the safe route as it's much harder for you center and surrounds to reproduce (a loud level) of 60-80 Hz.
As far as the small vs large...almost every manufacturer will tell you to set your speakers to small if you're using a subwoofer...and seeing as you have an HSU VTF-2, I'm sure it can handle whatever you throw at it...within reason of course
The strangest phenomenom is with my receiver the H/K 630 I need to set my speakers to small to send the low end signal from say, my surrounds, to the sub. But my friends Denon 3803 was sending (in DD and DTS) signals to the sub in both large and small speaker settings. Go figure. It seems to sort of break the rules, as it were. So really, every receiver appears to be different. But again. Industry standard = small.
