overshooting your mash temp should help with your conversion efficiency since that is largely determined by a-amylase activity and starch gelatinization.
I don't know if it's true, but I read somewhere that Budweiser uses a reverse step-mash, where they start high then lower the temp to get more fermentability. Would that work? On a homebrew scale would a mash that starts at 160 > 140 over two hours have more fermentability than a wort just mashed at 148 for two hours?
Intuitively it doesn't seem like it. I guess it would depend on what the starting temp was and how long you held it.
I think the beta enzymes get denatured at the hi temp and it doesn't work that way. At least it didn't work for me when I thought it might have been a brilliant idea a few years ago.
Yeah, that's been my experience, too, Jeff.