G'day all,
I've just bought a '99' Legacy (Liberty to all of us in Australia) wagon 5 spd non-turbo, and absolutely love it. I live in Australia's largest city, and around town my Liberty performs beautifully. Sure, it's not going to 'smoke' performance or other cars with more power, but it goes great. The lady who owned it before me had aftermarket parts fitted (her husbands idea no doubt, he currently owns two WRXs). My Liberty has a performance air filter, performance brake pads, sports suspension (with standard shock absorbers) and a rear sway bar. It has a lower ride height than standard Lberty's which makes it look much better. Coupled with the AWD, this baby sticks to the road and I love it. I am wanting to fit better shocks though at some stage.
On the highway, it cruises beautifully, although it revs a little too high for my liking when doing the highest legal limit in Oz: 100-110 kph (about 60-70 mph I think). It revs at about 2800-3000 rpm at these speeds. But as I understand, that is the nature of the gearing etc.
My Liberty is the equivalent to the current 2.5i; the latest GT in Oz has the 2.0 turbo. So if you go for the non-turbo, you get a bigger motor than the turbo (is this the same in the States?). Also, the GT wagon is slightely more powerful than the sedan in Oz.
So, if I was in your position, I'd go for the GT wagon, and fit performance suspension at least (STI make parts to fit the latest Liberty/Legacy, check out the official Subaru web site). I agree that it would probably cost more to buy the non-turbo and tweek it up to out perform a standard GT (in Oz you'd be looking at an extra $AUD20000 ($15000 US roughly) on top of the purchase price of $56000 ($43000 US roughly)). You are more likely to get a better machine by tweeking an already bloody good GT package (i.e. suspension, Unichip, brakes, exhaust etc). Also, the interior of the GT is much better than the 2.5i (in Oz anyway) and carries heaps more street cred.
Hope this helps,
Zik