I've heard all three decks you mention, and the Rega and Music Hall side by side with the carts you mention. The Rega is easily the best to my ears. But I don't like the Elys cart. And yes, I've heard the 10x5 and Elys on a P3-24.
The P3-24 and 10x5 runs circles around the others. The others seem slow, dirtier and flabbier. The P3-24/10x5 sounds leaner, tighter and cleaner. It may seem a little bass shy, but to my ears its tight and fast, hence the initial shy preception.
The TT PSU improves everything across the board. It easily brings it up a level.
Music Hall gear turns me off from a design and customer point of view as well. Pro-Ject is well made and Music Hall should also be, seeing as how they're made in the same factory, but they're not very reliable. 2 dealers I know dropped them because they had a lot of issues and Roy Hall 'may very well be the biggest pain in the ass in the industry' to paraphrase one dealer. Many others have complained about his lack of support and demeanor. He's the same guy who wrote a rebuttal to a review with an F-bomb in it to Stereophile. That's out there for everyone to read, so do you think he's going to be different to a customer?
Music Hall has to have design flaws IMO if there stuff breaks and Pro-Jects don't. They're made in the same factory.
I've contemplated upgrading my TT to a Rega, but quite truthfully I don't listen to vinyl enough to justify the cost. I'll probably get a P3-24 a little while after I get a BDA-1.
I auditioned several carts on my 1Xpression and the 10x5 blew them all away. It wasn't even close. Goldring, Grado, Linn. The 10x5 did evrything the others did and then some. Art Dudly (Stereophile) hit the nail on the head when he said "Wildly, highly recommended." There are very few blind recommendations in audio. The 10x5 is definitely one IMO.