Does anyone know if the GU 344 FC supports ultra PWM esc's ? I am trying to use one on a project with no luck.
No, only standard PWM ESCs. The GU344 has been around for a few years and at best is just a basic gyro only flight controller that is barely capable of making a quad fly. I have an original 330X that still flys but its not even as stable as the older KK flight controllers I have. Depending on what you're trying to do there likely a lot better controllers available now that cost a lot less than a GU 344 and will do the job better.
Ken
I just got into multi rotor flying. I started out with the 500X but I am getting ready to build a custom rig. What the best flight controller for the $$? I am going to run 8 motors.