Experimental Test :
Done in a multi-person brawl with a dummy 2nd player.
First test (Baseline) : Zelda first costume, vs. Toon link, no added computers, on Final D. time was counted in my head from the second I hit Down+B on my controller (using a wavebird)
1) Zelda --> Sheik : Time = 4 seconds
2) Sheik --> Zelda : Time = 3.5 sec.
3) Zelda --> Sheik : Time = 3.5 sec.
4) Sheik --> Zelda : Time = 3.5
5) Zelda --> Sheik : Time = 4
6) Sheik --> Zelda : Time = 3
7) Zelda --> Sheik : Time = 4
8) Sheik --> Zelda : Time = 3.5
9) Zelda --> Sheik : Time = 4
10) Sheik --> Zelda : Time = 3
Second Test : Picked Zelda vs toon Link again, and Buffered 2 dummy computers in the charatcer select creen, one as Zelda and one as Sheik, waited ten seconds then closed the computer slots and went to Final D
1) Zelda --> Sheik : Time = 3.5
2) Sheik --> Zelda : Time = 3.5
3) Zelda --> Sheik : Time = 4
4) Sheik --> Zelda : Time = 3
5) Zelda --> Sheik : Time = 3.5
6) Sheik --> Zelda : Time = 3
7) Zelda --> Sheik : Time = 4
8) Sheik --> Zelda : Time = 3
9) Zelda --> Sheik : Time = 3
10) Sheik --> Zelda : Time = 3
Third Test : Zelda vs Toon Link, final D , two computers, one as Zelda, one as Sheik
1) Zelda --> Sheik : Time = 4
2) Sheik --> Zelda : Time = 2.5
3) Zelda --> Sheik : Time = 4
4) Sheik --> Zelda : Time = 2.5
5) Zelda --> Sheik : Time = 3.5
6) Sheik --> Zelda : Time = 2.5
7) Zelda --> Sheik : Time = 2.5
8) Sheik --> Zelda : Time = 2
9) Zelda --> Sheik : Time = 3.5
10) Sheik --> Zelda : Time = 2.5
Obviously this is a shotty job at best, but what I can tell you from the sets and from what I've seen is that the buffering before hand in the load screen doesn't seem to make a big difference and in the end, even loading all of the characters...you're only saving yourself at MOST 1.5 seconds or there abouts.
so changing from Sheik --> Zelda seems faster , and the multiple comp characters definitely sped things up, but ultimately it's not that fast no matter how you look at it. Going from sheik to Zelda with full buffering is clearly faster however, almost twice as fast as the baseline.
the unfortunate part is that the practical applications of this in a fight are limited, but it does give you a decent chance of figuring out how far off the edge you have to knock your opponent off to make a safe transformation. the timing can still be variable however...
Comments/critiques / Questions / Flames ...whatever, post em up.