I think the Timex is the only one with the GPS stuff. I would suspect that it'd be a little less accurate than conventional cycle computers, that measure wheel speed with a magnet. Definitely sounds like an interesting concept worth reading about, though.
If I was going to the bother of having GPS though, I'd want to get a proper GPS with the ability to store trails, show waypoints/maps, etc. too though.
Most bike computer manufacturers (Cateye, Cyclosport, Vetta, VDO, etc.) have one or two high-end models that combine an HRM with a cyclocomputer.
I (and a fair few others here) use a Polar S710; they're a great all-in-one solution; there are a few little quirks to its cyclocomputer functions, but the data logging and PC software is second-to-none, and it makes analysis and keeping detailed training logs a piece of cake.
If you weren't interested in training logs and such, there is a cheaper Polar S150 with an inbuilt basic bike computer, and an S510 that has cycling functions and also some basic PC connectivity (but isn't that much cheaper than the S710.) Or else you could get a basic HRM as well as a normal cyclocomputer.
