Those RF amps do look wacky, but man did they perform. I've never sold them at any shop i've worked at, but they were great amps. My stepfather bought a 250a2 back in like 1997 or something, and he knows right about zero about car stereo. He hooked it up with with wire from Lowes running way too low impedence on some kenwood subs and to this day a couple trucks later that same setup is still banging away in his truck every day. He's so proud of his DIY job he wont even let me fix his rigging when I'm up there. So for that, I've got to respect the old school RF's.
Another older amps would be the Crossfire CFA-1000d, the white one with the yellow and blue flags on it. They were my first real powerful amps when i got into DB Drag. I ran 8 of those on a pair of 18" subs and blew lots of subs, but only ever lost 1 amp and it was my own fault.
In modern day terms, the engineering in the Robert Zeff designed Arc amps is incredible. The insane quality of the amps is what convinced me to become an Arc Audio dealer.