I had the Dinc2 for 6 days before I got the t-bolt.
Here is my honest opinion, if you're not going to be using the phone for data very often, and/or you live in an area where 4G won't be coming for a year or so, I'd go with the Dinc2. The battery life on the Dinc2 is better, the phone is a little smaller (in a good way I thought), the camera (video and picture) seemed better on the Dinc2 to me, the screen also seemed a bit sharper, and it just felt more "right" to me. Hard to explain it all really as they have almost the same technology. It also doesn't seem to have as many bugs as the tbolt. Also, for whatever reason the texting just seemed more accurate on the Dinc2 when in portrait mode...
That said, I'm happy with my Tbolt, its a GREAT phone! I just wish that my Dinc2 would have worked out, and then in a year or two I would have upgraded to another 4G phone.
Basically, if data isn't super important to you, go with the dinc2. If it is, or maybe you want the kickstand or the 4.3 inch screen, go with the Thunderbolt.