Titanium fasteners?

Seriously, that's a LOT of weight difference, and 2 mph isn't going to make that big a difference in how soon you get wherever you're going.

Wheels are traditionally the biggest bang for the buck, because they're rotating weight with a very large radius. But I thought you didn't want to throw another few hundred dollars at this bike?

Tanks are fun to drive (or so I hear). Just don't expect to drive them at Ferrari speed. Better spend your mental energy enjoying the things you can do on the hybrid that you *can't* do comfortably on the roadie, like ride in sand or gravel, strap on unwieldy loads, or run over random stuff.