that's a nice problem to have hahaha
You the only one doing guitar tracks? If so, based on that video I'd say the Diezel for riffing because it's got that dry, clear, "full range" kinda sound that you can double up easily , leaves more room for the vocals, and is more tweakable when you get to mixing. Then do your leads with the Mark where it's head and shoulders above the other two, and you know you're gonna have the soundstage to yourself.
I have no experience recording an Uber, but I know that my Mark III has always been kind of a pain in the *** because it doesn't like post EQ. That's the down side of the Mark 'focus'. You have to record pretty much the exact the sound you want in the mix and that's hard to know in advance.
