disclaimer: i own the dfv 2.5 mag, and feel that they meet all of my needs as a general surgery resident.
however.... i have borrowed a colleague's surgical accuity 2.5 mag loupes on occasion and i like them a lot. they are lighter than dfv, and the accuity is equivalent to dfv.
some of my colleagues have the new nike type dfv frames, and i think they look pretty cool. they are also lighter and imho more comfortable than the traditional black 1950s era loupes.
i chose the original dfv design not because i thought that they were necessarily better than any of the others, but because i knew essentially nothing about loupes when i bought them. my rationale for going with dfv, was that if the prs guys, the vascular guys, and peds guys all used them then they wouuld be good enough for me. and they are. but if i had it to do over, i might go for the nike models.
i agree that extended field, or greater than 2.5 mag is unnecessary for general surgery residency. the only attendings in my program who use greater than 2.5 mag are the prs guys, and on occasion one of our vascular guys pulls out the 3.5ef mag.