My guess on the statistics is that a very low percentage of the low hp blocks crack while a very high percentage of the high hp blocks crack. I doubt the curve is linear, most likely exponential. They probably all crack once you get above 900 hp NA. Maybe 50% of them crack at the 800 hp level and 25% crack at 700 hp.
My assumption on the % responding 'Yes' is these are all relatively high performance builds, or have had a pretty hard life. I've seen blocks with main studs & stock caps still show obvious signs of cap walk and the engines were (only?) making in the range of 500 to 550 HP.
I don't know if there is an obvious power level where the situation changes from "Yeah, they do that... " to "You better start looking for a new block... soon."
