i can supose that you had your hands on a pritchard (expensive) amp???
those very complex circuits can really sound like a compressed pentode output?
I wish I had !!!
And yes, they do sound on the same league of a very good Twin or Super Reverb on 6, in the hands of a skilled Musician, which is a very difficult task.
I suggest you get into their site, download and listen carefully to the many examples, specially the "Sword of Satori".
A lot of guys listen to these clips and find them unimpressive, it being "old guys" type music, (very tasty), no chest-thumping distortion, palm-muting, whatever.
For me, having tried to achieve true overdriven pentode sound for about 38 years, I find them miraculous.
Those SX amps are very good too, although Pritchards got slightly closer to the goal.
The Bluetones are called by some "a one-trick-pony".
Being that their "one trick" is to reproduce perfectly whatever a 50 Watt Plexi does at any level, we must applaud them.
I think they missed the point commercially, being that their only product is a 30 watt Combo, and that with a nerdy cheesy computer geek designed front panel, with a lot of blinking leds that turn it into a Science Fair project lookalike.
If they had made a classic styled 100W head, driving stacks of 4x12", they would be in *many* stages.
Can't suggest any Spice models, since I never learnt to use simulations.
Yet I think the current Pentode models *should* provide the answers, it's just that we don't ask the correct questions yet.
Teemuk knows a lot about it, having even written his own models !!!!
Phatt and Mensur also use simulations and practical on-stage experiments, to achieve interesting results.
Look around, there's also this guy whose name I don't remember this very moment

, who modeled a pentode with a bunch of op-amps.
Follow this SS Forum, there's a lot of cool guys experimenting along these lines, and now you are also getting into it.