I've just finished a Warmoth LP-cloner with a 24.75" conversion neck. I chose it in order to keep the guitar as close as possible to an LP, aesthetically and feel-wise (you do notice the frets being slightly closer together), but as regards differences in sound, as I've said here before, if you do the numbers the difference in string tension between 24.75" and 25.5" scales is only about 6%, so that effect will be very subtle. To give you a frame of reference, going from 009 gauge to 010 means increasing the tension by more than 20%. In other words a Gibson with 010s will have more tension than a Strat with 009s. Obviously the huge difference in sound between both guitars is due mainly to other more significant factors, pickups and woods being probably the most important ones.
I have a strat with a 24 3/4 scale neck on it and its great. I dont think it changed the sound much, just changed it to gibson scale.
I'm realizing lately though that I prefer the loger scale due to my fat fingers. I might sell this neck. Its a large reverse headstock USACG's strat neck 22 6100 frets with a chuncky asy. profile.
that's what i did about a year ago : put on a Warmoth short scale neck ( black Korina w/ BRW board ) on and older hollow tele body with Bardens in it and i like it very much. play a little smoother, plenty of sustain and since i ordered the new neck with stainless steel frets it also feels so much slicker i recommend it. cheers, the gitman