My wife got the Mesa GS (2005) just a couple months ago and it's a decent rig. She got it for $230! Via ebay, brand new, factory sealed, full warranty. It was so cheap cuz it's the 2005 model with deore rear derailleur. We did look at the 2006 though and it's basically the same bike except J1 rather than the manitou 6 and Sram rather than shimano. The sram stuff (x4?) is an improvement over the shimano imo, and it's nice that the brake levers are seperate from the shifters, on the 2005 it's the shimao deore combo unit. That's a personal preference thing though, you may not care.
Anyway, she's a newbie so she doesn't exactly barrel down hills but it's been performing nicely so far. The frame is plenty strong, the components are good enough, it even comes with decent tires and saddle. The biggest weakness is the wheels. They're just pretty cheap, is all. But I think they would hold up to moderately agressive riding for a while, long enough to save up for a pair of $100 deore/rhyno lite wheels or something like that.
One thing- the frames run small. She's 5' 6" and the 17" fits her. I'm 6 and the 19" would fit me well enough. The 17" feels almost like a bmx.
We also looked at the GT and like you said, the forks get lousy reviews, and actually it seems like the GT's frame is a step down from the schwinn. You wouldn't be wasting money if you upgraded components on the schwinn, the GT... I dunno, it just felt cheap to me.
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fun facts:
Psychopaths have trouble understanding abstract concepts.
"Incompetent individuals, compared with their more competent peers, will dramatically overestimate their ability and performance relative to objective criteria."