Ken's comments about "single signal" performance with the RAL reminded me of an article that explained how very precise control of regeneration can create that effect.  IIRC, the theory goes that one sideband was just barely in the oscillating mode (maximum selectivity) and the other sideband was not in oscillation, attenuating it.  Regeneration control is frequency sensitive, maybe this is an optimization of that ? .  I'll dig up the article and reference it to you all.