Very interesting and insightful information. After I blew up my first PS MTH loco with a Lionel "Z" I learned the hard way about voltage spikes and went straight to a Z-4000 that I bought from Elliot Scher way back when through this forum.
The wave forms that GunrunnerJohn show remind me of the old MRC DC power packs where they had a pulse setting to smooth out the running of older open frame motor locomotives. One could turn off the pulse for a full sine wave for more modern locomotives (this was in the 80's and 90's for me so modern is a relative term here).
To the topic, I use a Z-4000 for all my 3 rail and an old 180W DC power pack by PDH if I recall for my 2 rail. The majority of my locomotives at this point are 3rd Rail.
