I'm not really sure there will be much of a competition between the Fuze & the Pro. The specs on the Fuze are on HTC's Wiki & are pretty much identical to the Pro. As you already stated, the main difference is in the keyboards. The other difference is that the Fuze is *slightly* smaller at 4.02 x 2.01 x .71 in. Most likely due to the difference in the internal radio's. The other difference is that the Fuze will have Push to Talk, so if that's essential to you, the discussion ends there.

Edit: One notable difference is in advertised talk time. The Fuze specs advertise 8 hours of talk time, while the Sprint Pro advertises 4. If there's any truth to that, I could see that being a major reason to pick the Fuze.