Lionel 201 Switcher

Don, I can not answer your questions about locos not included in sets.  But I have a little experience with the 227 series of locos. The slug relay used for Magic Electrol reversing is the same relay used for teledyne uncoupling. My guess why this was tried in the prewar switchers is that there is not enough room in the slope back tenders for whistles. Most were equipped with bells, which were turned on and off manually. In my experience neither the remote reversing or the remote uncoupling is as gratifying as the air whistle. My guess is that Lionel learned this with the switchers, as they offered the semi scale 0-6-0 o-gauge switcher with both Magic Electrol reversing, teledyne coupling, and neither feature, so they could gauge the interest in these features.  Since neither feature was ever offered after the war, they may have learned the play value just was not there.