i have both and although i haven't measured them i'd say the 226 feels longer.
alot has to do with which stocks you are using. both my 226 and 96 are wearing hogue panels. the actual frame of the sig is smaller that the beretta as the hammer spring rides outside the grip frame...and is cover by the stocks.
the 226 is definately harder to CCW, in similar holsters, than the 92/96. the buttframe just seems to want to stick out more.