Well, I take back my earlier defense of the new coupler design.
I recently did a mod to my new sound boxcar for remote control described in the thread Remote Control for Lionel Sound Boxcars. In order to tow it around the layout for testing, I connected it to a TMCC upgraded RMT BEEP. Or, at least initially I tried to connect it! The couplers wouldn't close! After some grinding and filing, I was able to continue with my testing.