Based on your descriptions here, I think you eluded to your problem: It must be the area you live in.
I have Cingular service as well. I have used the 7290, 7100g, and currently am using the 8700c here in upstate NY. I have had no complaints with my voice quality on any of these devices.
I have friends who have Verizon and they get weak signals as well as poor voice service all over the area here.
This does support the idea that each service provider has their own drawbacks and it can truely depend on the location(s) you use your device.
Thanks for the review, it's a great one.
Good Luck on Verizon.
You had me at EHLO!