Okay, just spent like an hour and a half into my Palmer box and it's a keeper. Still figuring things out but the biggest surprise is how much gain there is available, it's like a Mark in that there's way more there than you can use and it's matter of balancing the types of gain you want. I wouldn't be surprised if an RA2 actually decreases the total gain a little.
Controls are ridiculously interactive, fortunately the manual explains it fairly well and you really need to read it-- it doesn't necessarily make sense at first to decrease woofy bass by increasing the treble, but there you go.
Cleans are the best I have ever played on an EL34 amp.
This isn't a "spongy" amp in any way, it's very bold and maybe a little stiff, but I'm used to a Mark III so no surprises there. You seem to dial out the stiffness by adding teeny bits of gain. It's easy to get a "thin" sound by being stingy with gain or master; that power soak is there for a reason.
The biggest difference between this amp and the Mesa tones I am used to is there's not a lot of the low mids. There's bass to be had and while they keep mentioning in the manual how tight the amp is I find it looser than a Mark for sure, and I don't think it would really like a 7-string; I tune to C# on a 6-string and the bass wants to woof. The upper mids are definitely prevalent and add a lot of complexity and colour to rhythm tones in a way a Mark just can't match, and it "sings" like a Recto generally can't.
I agree with somebody's comment that this is the amp Marshall has been trying to make since 1989. It won't be replacing my Mark III but I think I have a really nice JCM800 for sale now, and maybe even my JC77.
edit: Did I mention "unforgiving?" No? Very unforgiving of sloppy technique, especially on the crunchy tones. I think you might wanna look elsewhere if you're strictly a whenever-the-kids-let-me-have-time player.