i don't mean to demean girdles. i'd enjoy hearing more about the broken cranks and what type and brand they were. as it's been said a million times, the factory blocks were just never engineered to withstand that type of HP. don't take this the wrong way because 900+ HP is nothing to sneer at if it continues to work, but do you feel it would work as well in a heavy car situation as well as it does in a light chassis like a dragster.
i think there are pro's and con's to both steel and aluminum caps. we've seen a number of guys break the stock caps with what i would consider fairly mild motors at 650 or so HP. has that motor your referring to been torn down yet to see the effectiveness at reducing walk and or bounce of the caps?
people seem to forget that better higher tensile strength studs are available to help with the obvious issues. there is also enough material to go to a larger stud which does help. i'm sure harmonics plays a huge roll in a lot of block failures. unfortunately many machine shops just don't have the ability to dowel the mains either. it truely is a worthwhile investment if your engine will be on the edge of failure without it.
i'll be doing a mild RB 511 combo for my own car this year if you want to donate a girdle for testing , LOL. it likely won't be much over 700HP though. thats about all i'd want in a street pumpgas combo.
on another note, i applaud everyone thats trying to make improvements for the parts most have available to use.
and lastly, one of the problems that people just refuse to belive for the most part is that soft chinese forgings actually aggravate the cap bounce issue due to all the flexing that goes on. it causes a multitude of other problems as well. of course if your building a mild combo i guess it shouldn't be much of an issue.