In my experience, everything xc pro was awesome kit. Dare I say better than any Shimano equivalent.
The only issue was the rear hub and cassette due to the proprietary fitting.
That said, it lasts so if you did break out the expensive cassette you bought, it will probably outlast the bike.
Due to the freehub and cassette splines, plus the freehub design mating to the hub, there aren't any other options I'm aware of. Again, it's well engineered stuff with grease ports so if maintained, lasts ages.
I've run 7/8sp shifters with Shimano drive train and not had issues, it was good enough for the pace racing team bitd, and mint sauce too.
I don't recall having issues running a non suntour chain either, same goes for cables, though I did once have a build with full xc pro MD 8 speed with the correct chain and cables and that was just fine too.
Some say the shifting of you run a Shimano cassette with suntour isn't quite perfect as I believe the cassette spacing is slightly different, but I managed to get it running sweetly enough for me.
