TextEdit hangs when trying to reopen documents. Can I recover all documents except the one causing problems?
Eventually I gave in and told TextEdit not to reopen windows. It immediately opened, and the documents that had never been saved were still there. Only the named / saved documents had been closed. The document that was causing the problems was also open and usable, though I'm not sure if the paste operation had completed or whether it just had as much of the text as it had been able to cram in before the initial crash. 

The overall answer is that choosing "don't reopen" was safe. TextEdit behaved reasonably and didn't, as far as I can tell, lose any data.