I have had ST's and for long life on Bitumen you couldn't go past them....got over 70K and still have at least 10k left, as for chipping yes they do if you are even remotely lazy with your tyre pressures. I found they don't chip anywhere near as bad if you adjust your pressures accordingly. But for the last 5k or so on the black stuff were a little unsettling in the wet so as they harden up they get a little slippery.
No running something completely different mainly due to cost and wanting to try some muddies.
Cheers