I think unless someone has the unlikely opportunity to change out cranksets easily on the same bike, so that fit and everything is a constant, its probably not easy to get proper answers.
Until recently Nashbar USED to offer their own $60 ISIS mountain bike triple crankset (44-32-22), when they did it came in 170mm and 175mm options. Over the last five years I put two of the 175mm versions on mountain bikes I own and one of the 170mm versions on my Voyageur. I just switched out the 170mm cranksets with the lightly used 175mm one on my wall hanger mountain bike.
Sure glad I had that extra one handy, triple cranksets have suddenly become scarce. ISIS cranksets even more so. Why that matters is that two years ago I put a $150 SKF bottom bracket on that Voyageur, ISIS to fit the budget Nashbar crankset, according to SKF that BB has nine year's worth of use left on it, at least.
With respect to the crank issue 5mm of added crank length makes a surprisingly big difference.