I have the 02 WRX tranny...but I'm older and have NEVER dropped the clutch
I don't view the SVX as a fast car... just the most comfortable, fun, unique, and coolest Subaru EVER!!!
I would agree that the 02 WRX tranny is probably not the best choice of tranny for abuse. My 4th grinds a little when shifting in @ 5000 rpm, so I try not to do that.
Also, I know lots who would argue the other way. Guess it depends on who you talk to. Change the gear lube regularly and you'll be fine either way
As far as the upgrade goes, Read Hucks 5 speed install and you're home free. Lot's of good advice from folks here too. Once it's done, you will love it!