Does the Treo 600 only work in "data" mode in the Verizon National Access service area? This seems substantially smaller than where I've been told that T-Mobile has data coverage.

I'd like to stick with Verizon, but I'm having a lot of trouble with their rate plan. Sprint didn't seem like a good choice, but if they are sharing coverage with Verizon that is interesting - but is data coverage shared or just voice?