The Epic 4G looks to me like the right choice for now if you like a hardware keyboard (like the OP said, as a replacement for the N810). As for a happy N800 user, who doesn't feel the need for a hardware keyboard, but really wants as big a screen as possible in a pocketable size, the Motorola Droid X looks best. Only 2/3 the weight of the N810, but with a 4.3" screen, 0.4" deep instead of 0.55", and just a tad narrower -- seems like the best form factor to me.

Of course, I'm not actually getting one. I'm still satisfied with my N800 (and have come to like the N810, too; just set one up and gave it as a gift), and I want a phone-less tablet. But the specs on the Droid X are so much to my liking that I could see buying one, if it will work without a contract, and using it just with WiFi.

(I'm still hoping for a MeeGo tablet with specs like the Droid X, and no cellphone, and can wait a while longer.)