[Paul Durham]

The P37D is plastic but superior in quality and tone to other less expensive instruments, Though if you watch for a good deal you can acquire the yamaha P37D for only a few dollars more than the Performer. Do you like a more resonant tone. That is the main difference in having a metal case. The build quality is pretty much the same. Longer service is the number one reason to upgrade. I have all 3 in my collection.