Thanks for the info! I didn't know Sykes experienced both flavors of Mark III Coli!
The blue stripe was basically my go-to for 2-3 years, and the amp that lives on the Mesa 2x EVM 2x MC-90 cab, so for the most part I agree with that sentiment and my heart lies a bit more with its over-the-top nature. But sometimes on that cab it could be a bit too brash -- it seems weird given what I expect from those speakers spec-wise or even my experience with them when they were in separate 2x12s, but at the moment that cab is one of the harsher cabs I have. The blue stripe into that can definitely be an ear fatiguing experience. But then the no-stripe into that feels right, and the blue-stripe into the 2x12 with DV77s feels more pleasurable - still has the cut, but not making my hair stand up on end when playing on the top strings either
So I think people who want like an 80s guitar virtuoso sort of sound are going to like the blue-stripe more, and people who want to sort of round out a Mesa collection with a new flavor are going to like the no-stripe a bit more, but for me changing the speakers around can do a lot to move them into either direction. The geqs don't seem to be enough to really alter the inherent voicing of each model though -- I can't sit there on the same cab and tweak the EQ and get them to sound particularly close to each other. The best way I can describe it and what my friend agreed with when we were A/Bing, is the no-stripe probably can sound closer to the master of puppets recording, and the blue stripe probably sounds closer to what you want MoP to sound like.