As far as noise goes... nothing really out of the ordinary on mine. I have what I believe to be an STi 12.5lb. flywheel (at least that's what it looks like)... HOWEVER, I also have an STi vIII 5mt from 1996 with the older style case and 4.44FD, so it may have been built somewhat differently (I'm sure their manufacturing methods have changed at least somewhat between 1996 and 2002). I run valvolene 75w90 and 1qt. of pennzoil synchromesh. I did notice a lot more gear noise with Uncle Scotty's cocktail before switching back to valvolene/synchromesh, so I'm not sure if a different fluid may ease the noise a little bit.
They keep "refining" the 5mt... but based on my experience, I'd say they're going backwards. The older trans seems to be less noisey, less clunky on the shifting, and generally more well behaved than any of the newer suby 5mts that I've driven. I think it's just the way gear lash is set on the newer transmissions, plus maybe other manufacturing tolerances involved that cause the decel noise problem.