I've played the G5's, the i-10's, the G25's, G30's and the latest model G's.
The differences... as the lofts have become stronger over the years - not a lot of difference as far as distance, providing center-face contact. The biggest difference is (imo) the higher launch angle because of the design of the more modern game-improvement variety. And, of course, for those of us who can't find the center of the club face every time - the oversized face helps mitigate a loss of both direction and distance on off-center hits.
You just have to be a little more precise with the smaller club head. And... it might be a little easier to shape shots based on L-R or R-L. But you're still dealing with a cavity-back design, and cavity-backs were more or less designed to help hit a straighter ball... so there's not nearly as much influence with the design as there would be with a muscle-back or blade design.
That's really the primary difference.
Of course - the newer stuff has jacked-up lofts and there could be 1/2 club difference in yardage based on older models vs newer stuff.