Well, since DWR doesn't do widgets at all (aside from some integration with a GUI library or two), I'd say Dojo wins, heavyweight and all
If you're talking strictly about AJAX with Dojo vs. DWR performance-wise, I have to admit I've never done any real comparison to know. I *do* know that DWR performs extremely well, as does Dojo's AJAX functionality. I think it would depend on how lightweight your code is when using Dojo (your server-side code I mean). DWR is doing a good bit of reflection magic and dynamic generation of code and such, even with caching involved. So you never know. I've never seen poor DWR performance though, that's for sure.
As for whether you can use Dojo widgets with DWR, the answer *should* be yes. The Dojo guys are pretty smart and I'm sure they haven't intrinsically tied any of the widgets to their own AJAX functions. It should also be noted that DWR now lives under the Dojo Foundation, so it isn't crazy to think there will be some sort of enhanced interplay between them at some point (don't take that as a hint that anything is imminent or that I know anything no one else does, this is nothing but conjecture on my part).
You showed up just in time for the waffles! And this tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop