Hmmm, thats interesting.
I just use the Prestone Mixed (btw its actually about 2 bucks cheaper a gal than the full concentrate). If you're running a highly modded car, it mite be a serious issue, but I really don't think that the type of coolant is going to make a huge deal for just street use. Unless its DexCool....
Yes, DexCool is satan, I believe the intake mani, or something like that, on our GM minivan crakced, and somehow allowed air into the cooling sys, completely screwed things up.