I love my Prime. I do experience random hangups (really only when browsing, I guess I should check out some other browsers, but, I like the stock one a lot).
WiFi strength is not the greatest, but, I haven't really experienced the slow browsing, just generally only 2/4 bars.
Bluetooth tethering gives me issues. It does not like to stay connected all the time, and, once it stops working, it's a reboot to fix it (hopefully).
I don't use it's GPS, but, I do keep the dongle in the case with my Prime, just in case. I mean, it would be nice if it worked better since it's something I paid for, but, I'm not too bent out of shape over it.
Other than those issues, it was a great investment. I use it constantly. The dock is a great selling point too. It's what initially made me investigate the Prime. And, now I don't think I could own a tablet without one.
Sounds like a decent trade. Like dbattenfl said, see what the prices are like, if they are comparable, and, you have no need for two phones, then go for it. Then again, you don't really need two tablets. I guess you could trade that to someone else.
Or, use it as a dedicated device. I was reading an article on that the other day, things to use your old tablets for. I could see a lot of use for an old tablet in the kitchen.