My experience was that regens offered good performance for a simple circuit with only 2 or 3 active devices. On CW even in the crowded novice bands of the 1950's they worked "OK" even as long as no very local novices lived within a few blocks, and even then I could sometimes get by. My experience was that they could often work OK with a rather short random wire antenna, like for portable operation. A full size 40 meter dipole tightly coupled to the RX was just too much. We often just used a "gimmick" capacitor of a few PF to couple the RF into the receiver and this "solved" many overload problems. (the capacitor was just an inch or so of 2 wires twisted together a few times). Also back then nearly zero percent of the novice population had good commercial receivers with any significant selectivity, so we could hear a good percentage of the audio spectrum at one time, perhaps all the way from much less than 100 Hz to possibly 10 KHz. We fully developed our brain filters and could copy many different CW signals 100 % without touching the dial. This did have it's limits !!!. Years later we discovered Q multipliers, 50 KHz IF amps for our "creations", and even the crystal filter, which made single signal reception possible. The 40 meter novice band back around 1954 and 1955 was only 25 KHz wide and had thousands of stations every evening, and our transmitters were crystal controlled, so after a CQ we would tune up the band slowly and often find an answer 5, 10 or more KHz above our transmit frequency. One thousand mile QSO's common, but coast to coast QSO's were not rare, and many novice ops. with perhaps 25 watts, a dipole, and only a few crystals obtained WAS certificates. I now appreciate my crystal filters where I can listen to one signal at a time, but for casual operation still just use my 700Hz or 2700 Hz filter for casual operation since I like to know what is happening up and down the band a bit. I got off the regen topic, but it is important for CW operation to set the regen control just at the point where oscillation just begins. This gives some moderate selectivity, but in our old crude regen circuits, moving the frequency slightly also required a re adjustment of the regen control. Long live the regen KL7CW