Hi krewskater!
I would be tempted to keep the Thrive if you like it. I haven't looked at its specs, but it sounds more future-proof, which seems to matter to you.
I love my EE, don't get me wrong. And for $170 it is worth it for the large e-ink screen alone, but not if you have to give up another device that does other things that you also want . . . you know what I mean??
One point: The EE is not as prone to WSoD as the PE (I believe). Instead, it has more issues with hibernation and browser crashing.
Gonna look up the Thrive now.
Edit: Hmmmm. HDMI, Flash, probably handles any app you want . . . fast, company support . . . . I'd keep that puppy!

On the other hand, I would try to find the cash for a big eDGe too -- but for me reading is a priority.
Good luck! I hope you'll be happy with whatever you decide.