Well, in this hobby, "more" and "better" are always a question of subjective perception.
Nevertheless, Alex has written this and I think it gives a good picture. In addition, I would generally and intuitively say that the difference could be significant for me, so yes: "much better".
"MK3 vs Mentor Multiverse – To my surprise after mentioning that I’m reviewing MK3, I got a number of questions asking me to compare it to UM’s flagship Mentor Multiverse. Not sure if people are looking for a scaled down budget version of MM or maybe they want to complete their UM IEM collection. Staring with a soundstage, while MM is a little bit wider, its imaging is more holographic, something Mentor excels even relative to other flagships. With the bass, MM has a stronger mid-bass punch, but MK3 still holds an upper hand when it comes to sub-bass rumble, going deeper and being more elevated. While both have a balanced sound tuning, MM pinna gain gives upper mids more boost, bringing vocals even more forward relative to MK3 and giving them slightly more body. Their treble is close in quantity, but the actual perception is slightly different because bringing mids slightly more forward in MM pushes treble a bit back, while the opposite is true with MK3 where treble has a bit more energy.
But overall, while tuning is a matter of a personal preference which makes it hard to decide if one is better than the other, from a perspective of a technical performance, the flagship MM is a noticeable step up in comparison to MK3. And for those who like to correlate improvements relative to a price difference, please keep in mind that as you go up in price there is always a factor of diminishing returns."
https://twister6.com/2023/07/22/unique-melody-um-mest-mk3-mkiii-cf/3/