On the one I just finished, I did hand sew the miters closed, because I was following a tute by Sharon Schamber and she said she hand sews the miters last. They looked like they weren't going anywhere, but akrogirl makes a good point that nothing can catch and tear them if they are sewn closed.
I got great results by starching and using glue, as Sharon said to in her tute... Nice smooth perfect binding and no puckers!