After catching up with the thread, I'll stoke the fire some more.

1. From reading that last post by the OP, a new bike would be lighter by default- even fully loaded. If current one is 40 naked, a new one in her budget would easily drop 10 pounds off of that.
2. The OP prefers Trek, but I"m wondering if she is limiting her options by fixating on just that one brand?
3. If you like riding the mtb, then maybe try to find an older, rigid one. Bunch of people here use older 80's and early 90's mtb as commuter rigs. Use slick tires
4. I can't remember, but does the OP's 7100 have the suspension bits? If so, they are more than likely the cheaper kind that can't be locked out...