Aristotle, I don't think the recording sounds too dark at all; it sounds natural, as opposed to the in-your-face mids that a 57 puts out, but a blend of the two mics is also not a bad thing of course!
What I like about your new amp is its clarity. It's a more open sounding amp, with a brighter, spankier top end than most Marshalls.
On the other hand, there's a certain vocal quality that your MDT has shown on other recordings that I like quite a lot. You're right about the whole thing with new amps. It's always, "Step up to the plate, Next Shiny Object!"
Lately I've been rediscovering and appreciating more and more the tone of my DG30, and what has really led to the way I'm feeling about it has been how it responds to the recently-acquired Suhr compressor pedal. I find that it smooths the overall frequency balance of the amp in a really distinctive way, and thus I'm using the amp for a few things I wouldn't have before. It's also a great match for the 30th CU24's pickups and configuration, and that guitar has become my everyday go-to.
So right now, the DG30 has been my temporary #1, having even more uses on tracks than my beloved HXDA.
But then...today I played the HXDA straight in, guitar>cord>amp, and remembered why I love it so much!
I get use out of the Mesa Lone Star, too, but it's a different kind of thing of course.