I actually just transitioned from a Droid 1 to a Droid Incredible (not an upgrade though, it was a replacement after many failed D1 replacements). I never rooted my D1 so this comparison is strictly from my experiences with the stock phones
Pros of Inc:
-Faster processor, everything is quick and responsive
-Very smooth UI. I really like HTC's Sense UI and Widgets.
-8MP camera instead of 5MP. Camera is also faster.
-Slimmer form factor
-8GB Internal memory in addition to SD Card, for a possible total for 40GB.
Basically, everything just runs smooth and quicker. There is no lag between switching apps or returning to home. HTC's Sense UI is very well polished and includes some great widgets (but I guess thats subjective based on the above post).
Cons:
-Notification LED. Color cannot be customized (only red or green) and it is significantly less bright and harder to see than on the Droid 1.
-Phone vibration is weaker. Probably due to the slim, plastic body vs the heavier, metal droid.
-Battery life is worse, but thats subjective of your use.
-Phone feels a little cheaper because its plastic.
-Known to have random reboots. Mine has done it once so far in the week I've had the phone.
-No physical keyboard (though for me, this is a Pro since I never used mine on the D1)
Overall, the Inc is definitely better than the Droid, however I don't know if it's worth using your upgrade right now. Its almost 6 months old already, and with smartphones advancing as quickly as they are now, there should be some nice phones coming out in Q4/Q1. And if you're open to rooting, you can probably overclock your Droid enough to be comparable with the Inc's speed.