Amp history is funny. After I got into the Gibson history, it seems they have inspired about every guitar amp maker that came after, including Fender, Vox and Marshall. They did make fine bass amps early on too. They did not explore high gain or agressively voiced amps, simply because they did not want those tones. As for early high power guitar/bass amps, there are some romantic stories that makes some people think Marshall or Fender were some kind of pioneers 'inventing' 100 watt heads in their shops because young soon to be famous players couldn't find loud enough amps. Can't say there is much difference though, between a 100w marshall head from '65 and a philips head from '55, except the philips ones are more compact.
As for class D, from a service perspective... I see the rate those yellow amps break down, and support is non exsisting for a lot of brands. Some, especially smpeg after Yamaha took over, have good support though. Nowdays, I carry a portaflex 350 class D as a backup for my Superbass 100 because of weight. It has a replaced motherboard, sounds OK but is not really louder than the SB. I think that weight is the only reason to taking class D serious, but they break down and pile up at such a rate that it's a threat to the environment 🌲🌲