So how many use MM cartridge and intend to keep it that way ?

I am raising my hand.
But I also run a ZYX UNIverse and love it too, on a different turntable.

Makes sense to have two arms or two tables, doesn't it?

Hmmm...

I have never had a turntable with anything other than an MM cartridge so I have to ask, is there THAT much of a difference?

Me neither.. curious now. Damn it.

IMO, Every single cartridge brand and type, regardless of how it works (MM, MI, MC), sounds at least a little bit different from any other cartridge.  Whether that difference is worth worrying about is subjective.  Among the different types, I have found, thanks to Raul et al, that I prefer MM and MI over all but a very few MCs.  ZYX UNI is one of those MCs I like a lot.  Funnily because it displays some of the best qualities of MM/MI.

Inna, Makes sense to me to have four turntables, actually.  But I am nuts.