The shop I work at sells Fuji and I'm pretty familiar with both the LX and DX. I really hate the brakes on the DX, they feel like crap. The LX is a pretty badass bike. The ones we've sold have never come back for even minor repairs. Both of them have adjustable stems that are borderline garbage, so I'd recommend swapping those out, unless you really like them. They typically just come loose. I also dislike the gripshift on the DX, but that's just me being a snob.

I know nothing about the Trek, or their goofy number system.