lookin' good bro. i'm digging that rear wing, it's a very euro style.
as for lgt vs sti... lemme tell you, the lgt is going to be way roomier and comfier than an sti. granted, we're comparing a midsize sports sedan to a 5dr sports compact. NVH (noise/vibration/harshness) will definitely be a lot higher in the smaller car. however, aftermarket support is a lot greater for imprezas than for legacies, and both can be made to be just as fast...
usually i'd say "boost what you got" but given the high cost of boosting the 2.5i (those AVO kits sell for $3200), trading up will be much more economical. plus you might get lucky and snag a manual transmission LGT, which are f**king rare as hell, especially in wagon form. hell, i live 3 hours away from the subaru plant where legacies and outbacks are made, and even i can't find a manual lgt wagon.