That last bit you said - each of the digital models seems to behave very differently from each other - that's a very good notion. That is, IMO, the biggest plus but also the biggest nuisance to any digital modelers.
These days the modelers, hell, even VST plugins handle the revered 'picking dynamics' very well, that isn't the problem...the problem is that the models themselves are rather rigid. You _can_ change the sound by playing and such, and whatnot, but nevertheles...you always need a different patch for each song almost.
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With modelers, I think I can get even a better sound than 'real' at least on recordings, but still, it's always just for that song I'm working on. Almost always when I bring up the saved patch for another song, it just won't work no more. I always end up browsing thru the amp models for that particular need.