I have both the DX and the TB and based on my experience, the TB makes the DX look slow when it comes to everyday task not involving the internet like homescreen switching, accessing apps, etc. Even with the 3rd party homescreen apps on the market, I still prefer my Sense over Launcher Pro Plus and ADW EX, etc. Don't get me wrong, the DX isn't a slouch by no means at all. Besides having less RAM and a older chipset, I think the biggest difference is that HTC built Sense to fully maximize its use of the chipset. Because this TB was built to fully maximize its chipset, the battery life suffers, but you will be blown away at how fast the TB is.
The DX does have a better battery life hands down when it comes to utilizing the phone performing everyday tasks. In standby mode the DX still manages to conserve battery better than the DX. To put it more into persepctive, I use live wallpaper and auto brightness on the DX, but not on the TB because it drains the TB battery much to fast for me with the phone display brightness set at 20% and the DX still manages to have a longer battery life than the TB.
I don't live in a LTE area, so I can't comment on LTE speeds. But as far as 3G speeds go with the DX vs TB, the TB browser in general jumps out ahead on loading pages, but ends up finishing at the same time the DX does.
Camera quality as well as video quality were about equal, but then again my eyes aren't trained. I think the DX would feel better in most people hands because it isn't as wide as the TB, but the TB screen ratio is better suited for viewing video, etc.
My only gripe about the TB is the battery cover is a pain in the rear to take off. For people that plan to root, the TB is the wave of the near future. For those that are looking for the fastest and smoothest phone on VZW, the TB is for you. For those that aren't into rooting and just want a fast phone, I would recommend the DX unless you are looking for the latest technology. For those who want the best battery life, the DX is the way to go especially with the DX2 about to surface here in the 2nd quarter, which means VZW could pratically be giving DX devices away to keep up with 3rd party sellers like Amazon and Wirefly, etc.