I have never had a DSMX Powersafe Rxer "main unit" fail and I have lots of them. I have had a remote Rxer fail, but it did not result in loss of control as the other two were still working. However, I do use DSMX transmitters. Other than the one remote, I have never has a DSMX receiver fail and I have dozens of them.

One of our club's Jet Guys just last night called me about troubleshooting a 9 channel JR Rxer main unit that apparently failed. I'll probably hear more about that tonight.

I have seen a frame loss show up once when I was way out there with a Giant. I typically use fades to check the positioning of the Remotes within the airframe. I have a transmitter alarm set on frame loss. Get that alarm and it had better be heading back at me.

A remote failure will not result in a Rxer failure. A remote's cable connection will not result in RXer failure. Redundant batteries eliminates a switch failure or harness connection failure.

Have you tried a full power range check (i.e. plane ~1/2 mile downrange and see if the controls still work in normal transmit mode)

If the RXer failsafed at straight and level, how do you account for the last abrupt turn down?

You did not say how the Remote Rxer's antenna were oriented. 3+ Remotes should = 3+ different orientations.

Personally I would send the Rxer and transmitter back for testing.