No I think the JC-120 probably got it mostly right, but the cheap way to do a SS amp is a jellybean opamp into a jellybean class AB power amp IC. From there, development dollars went to onboard effects, zillion channel EQs, and other gizmos. But I don't think there is anything known about basic analog SS design today that wasn't known in 1975.
Of course there are lots of sexy things that can be done with DSP now, and that's still what you see in modern SS amps. Also with switching power supplies and class D amps you can push efficiency beyond 80% which makes for a much lighter amp, couldn't do that in 1975.
But you don't see a lot of back-to-basics build a good sounding circuit with gradual overload characteristics, because (forgive me) as Billy Joel sang, "you can't get the sound from a story in a magazine". But you can see a picture of an LCD and iPod dock . . .
I've pretty much chucked all the SS designs I was playing with earlier in the year because I doubt anybody really cares. Then I thought hey let's do a 21st century (but still all-analog) vastly smaller version of a Rockman that unlike the original doesn't sound like a piece of overcompressed crap, but hey, modeling headphone amp that dangles from your guitar jack for $39. Pretty hard to compete with that . . .
So I write simple little VSTs and combine those with commercial VSTs and that keeps me happy. I find one secret is just use the amp sims only for effects, cab models, and distortion, and use general-use high-quality EQs, compressors, and verbs around that. Because when you are writing a plug, it almost doesn't matter what it is, you tend to give yourself an upper limit on CPU per instance. Let's say that's 2% or whatever. So if it's an all-in-one amp sim, you have to do 30 things with that 2%, but if you break it down into a bunch of pieces that each can have 2% (and maybe 10% for the verb), you should be able to do a better job. That's my random theory anyway.
Also, distortion algos (compression too) always need to oversample. So if your amp sim doesn't, time for a new amp sim. Or you can just record at 96kHz and downsample after processing, that generally works pretty well too.
The hardware analogy would be to use analog rack gear around the modeler . . .