I will throw in my two cents. Bob Carver is a talented engineer. His Magnetic Field Amplifiers were nothing magical, they just used multiple rail voltages to reduce consumption and heat. They are called Class G. They always sounded fine to me, and with the exception of the M400 cube have been reliable. There is company, Nelion Audio, LLC, that performs rebuilds (new caps and any needed repairs) and upgrades to increase their reliability and power for reasonable prices.
The Sunfire amps were great. While the tracking downconverter is a neat design, others use them now (Class H). Emotiva uses such a design in their Differential Reference amplifiers. I acquired a used Sunfire Stereo for $700 nearly 20 years ago to use temporarily while having an Adcom 5500 upgraded by Stan Warren (the other half of PS Audio). The Adcom came back, was hooked up, pulled back out and the Sunfire stayed. More power, better sounding (in my flawed sighted testing, but I will say I expected the Adcom to sound better, many will say I didn't let the Adcom break in long enough since I only gave it a few hours), cooler, and had the cool, but useless, Joule storage gauge. Last year I spent about $400 to have Bill Flanery recap the Sunfire and continue to use it as my amplifier for my Magnepans.
Bob is also good about supporting prior products. When Sunfire went away, he set Bill Flannery up with all the information so he could have his own shop doing repairs. He did so previously with another company when Carver went under (long after he left).