Well, although I have never, yet, used an RU, I DID use an RAL-7 as my main and only station receiver for some 12 years.

I believe the circuitry is very similar: a 6 tube TRF: 2 RF amp stages, a regenerative detector, 2 stages of audio, and an "AVC" (a limiter).

The RAL-7 was designed by RCA. It covers from 300 kHz through 23 MHz.

I never had any trouble separating AM, CW, or SSB stations with it. The user simply has to learn how to use the regeneration control.

I really liked the receiver. For one thing, it has this "transparent" sound: there didn't seem like there was much between you and the signals on the band. 

Ken W7EKB