^ i suspect it's got a ton of modelling in the preamp section. from what i can remember about reading about them, anyway.
Personally, I wasn't all that fussed. the lower gain tones were actually not bad, but i thought the higher gain tones were fairly poor. I'd rather have a channel switcher. I know when i tried the spider valve, you could have got an engl screamer or laney tt for a similar price, but i think the prices have changed a bit now, with the spider valve getting a bit cheaper and the other two a bit dearer. neither of those two do any modelling, but i'd rather have a good clean, good crunch, good heavy crunch, and good high gain tone, than 16 (or 32? :-?) mediocre modelled tones. That's just me, though.
I did only get to try the spider valve at pretty low volumes, though. and i didn't think it was terrible, it was a lot better than the normal spider, i was actually surprised how much nicer. Just no cigar, kind of thing. :lol: