Peter_IK is, of course, right -- though I think we are all talking at cross-purposes.
The Metal V 1, 2, and 3 were all (as far as I know)
originally designed to represent different kinds of mic'ing techniques on the same kind of physical cab. So, yes, they
all sort of have the tonal characteristics based on different mic models/placements "built in", but that how things were in the AT2/Metal era, before distinct and movable mic models came in with AT3, and speaker modeling with AT4. You can't record a guitar amp without a mic, so without separate mic modeling, you have to account for the "existence" of a hypothetical mic
somewhere in the model. And the cab models are, as Peter_IK says, "a combination of impulse and modeling technology". In this sense they are all "identical" in the sense of how they were conceived as working in combination with the amp head model, etc.; they just sound different by design, too. So, anyway, there is no rationale for picking any of models 1, 2, or 3 over each other except in how they sound for your purposes.
However, in AT4, as again Peter_IK says, even the legacy Metal V 1, 2, and 3 "cab" models can have their speakers swapped out with other speakers. That is, they now function just as individual cab models, like any others.
So, this may all seem confusing
but it's just an artifact of how the technology has evolved over the years. IMO, the sensible thing to do is to forget the original usage-case intentions (i.e. of different mic types/positions, etc.) of the Metal V 1, 2, and 3 "cab" models and just treat them as different kinds of "cabs". After all, after years of use, abuse, maintenance, etc. real individual physical cabs can end up sounding quite different in practice.
Yes, it would also be nice if brand-new models of "based on Peavey" amps/cabs came out, if only because the newer Amplitube models are (IMO) rather better than the ones from .... 2007? Or thereabouts for Amplitube Metal? Anyway, I mean, we might well expect to be able to hope that the models and modeling would get better over the course of a dozen years!
So, head over to the official wishlist thread (if you like) and put in a vote for a new "based on Peavey 5150/6505" amp/cab model combination.