There was a bug with DavisTuner working with L firmware for the 650, but I fixed it in version 1.1. What version did you try?
Yes, you can still get it from my site. It's odd that you didn't see a big improvement from using it...
Au contraire, Nick, I'm sure it was the fault of DavisTuner.... :) It certainly sounds like a bug.
Try the new 1.1 version. I know I fixed a bug, I thought it was only with the L firmware, I'm not quite sure.
Another possibility to try is to start with the firmware file that I sent you, and then make modifications to that.