Me, not wanting to get too involved in pixel adjustments, I have taken the stance of letting designers adjust pixels all they want in products like Frontpage, Dreamweaver, whatever.

When they hand me funky-browser-sensitive HTML it is their decision and not mine. HOWEVER, I still need to take their stuff and make it work in final system...which is primarily template driven.

So the first time around I'll templatize their design. Then a series of subtle changes will follow - pixel moved here or there. You know, the usual stuff. Tag Compare might help you spot these little changes.

So, although this may not be of much use on identifying, and avoiding browser idiosyncracies it may assist in accomodating some of the designer's needs quickly and accurately.