Music Hall MMF-2: How much can it be improved?

I would say your best bet would be to upgrade to a more expensive model such as the MMF-5 or 7 or go for a used vpi or other table of your choice and enjoy the ride.

I had a MMF 2.1 back a few years ago and tried a Shure M97XE on it. It wasn't much of an improvement, and I've heard the same cart sound better elswehere. I agree with the general sentiment about the arm on this table being a big weakness. It is what it is - a serviceable, affordable table without much upside beyond what's delivered stock. Given that there aren't any upgrade arms compatible with this table, it's a bit of a dead-end. I tried an upgrade mat as well, couldn't hear any difference. Don't upgrade it, replace it. I'd look at brands with more flexibility.

My current turntable is the Dual CS530 fully automatic belt drive turntable. I messed up with the anti-skating and it does not function properly, so I've been looking for a new TT.

I've tried lower versions of Grado (Black and a few lower ones) and Shure cartridges on the dual. Some differences among them, but not huge. But when I tried Shure M97XE, there was a big difference. I consider Shure M97XE as a good mid-fi cartridge, and by far it was the best cartridge I've tried.
I think Goldring Elan is about the same quality as Grado Black cartridge.

Am I wrong if I assume MMF-2 is a better TT than Dual CS530?
Well, actually I just bought MMF-2 and it is in transit. I also bought a Grado green cartridge and Shure V15-III, so I'll see if MMF-2 makes any difference on those cartridges.