I just bought a Touch on Saturday to replace my 6700. For me, it came down to:
* I hated the 6700's keyboard. I use Block Input exclusively, and used to crash my 6700 all the time by accidentally sliding the keyboard out *just* enough to trigger an orientation change, then snapping it back in and accidentally pressing one of the side hardkeys while WM5 was still trying to gather its thoughts and do the orientation change.
* I have unlimited data w/PAM, and if I'm someplace where EVDO or 1xRTT data doesn't exist, chances are there's no WiFi I can use, either, so the lack of WiFi was no big deal.
* The Touch uses the non-slippery black plastic I love. The Mogul uses the slippery plastic I detest.
Take all the above, and add the thinner form factor, and for me it was a no-brainer in favor of the Touch. But if you really like the 6700's keyboard or need WiFi, you should definitely think carefully about how the lack of both might affect your daily happiness.
One suggestion -- spend a week with your 6700 using ONLY Block Input or one of the soft keyboard modes to see how much it really bothers you... keeping in mind that the Touch *does* have at least one new text-entry method (20-key) that you might like if the 6700's choices leave you dissatisfied.