My friend ran KB's in his sbc the past two seasons. The first season he broke two pistons and destroyed the block in the process. He bought a different block and a new set of KB's. At the last race this year his car started ticking the same way as it did last year. Turns out he broke two pistons again along with destroying another block. Something to think about.
But then for every guy who has had bad luck with them there are those who swear by them.
"Will these pistons live at this level of performance with street and seldom strip use? "
Probably.