I think Gen. II fork tubes are larger in diameter . . . also, men say the later suspension has less travel (by about an inch, IIRC), but . . . this reduction in travel is accommodated by pre-load and valving considerations, offering a better suspension . . .
Maybe not exactly "Tweedle Dum and Tweedle Dee," but--how much performance improvement might be gained?
A two-piston caliper, vs. a one-piston caliper appears an advantage, but--day and night?
Build your own decision tree; how much improvement is worth how much effort?
Unfamiliar with the Gen. II ride, I don't feel I've exhausted the capability of my Gen. I, so far; sincerely, YMMV (Your Mileage May Vary).
By all means tell us what you've done, and how it worked out.