I'm pretty sure the issue w/ the keyboard and the messaging app has more to do with the messaging app. When I first heard about it, I tested it with the three different keyboard apps that I had and was able to replicate it with each. So I assume it's just one of the many bugs in the messaging app that popped up with the GB update. The best suggestion to work around these bugs is to use a different messaging app. I've been using Handcent pretty much since I've had my phone and don't experience any of the issues others are reporting with the stock app.
As for the random lockups, is it possible that an app you've downloaded from the market is the cause? Even though you replaced the phone, your apps from the market will usually automatically restore. If there's a bad app, then it's a good chance it'll cause the same problem. You're not using any type of task killer app or anything like that are you?
Personally, I haven't come across any recurring issue that I haven't been able to resolve or work around. Most issues have been with the stock messaging app, and like I mentioned, by using Handcent I don't encounter those problems. If you don't want to use 3rd party apps then maybe going back to the iphone is the best option for you. If you're willing to do a bit of research and troubleshooting, I'm pretty sure you'll be able to find a solution to the issues you're encountering and get the phone working in a way you're happy with.