That's still a heavy car for not having AWD.
Subaru addressed their lean issues with this year and I used my Access tuner stage 1 reflash to help the STI and the datalogs show no detonation.
On a tight twisty track a FWD car can be vetter than an AWD car but AWD makes even a so-so driver good,you need to be a very good driver to get the FWD around the same track. I autocrossed my '93 Mitsu Eclipse AWD and it was much easier to drive at the limits then my fwd Type R which required alot more attention.
The AWD has a big margin for error and is easy to correct when it gets loose and it's a true all weather car since you can track it one day,hit the dirt the next day and then it still can get you to the ski resorts with no issues. If it's your primary car in an area that sees snow regularly AWD is a must for me
For the money I'd still take the WRX but that said the ST is still a pretty sweet car and I like it in red.
'12 Focus Red Candy SE Sport 5 spd
'99 Toyota 4Runner Sport
'11 Subaru WRX STI Hatch