5 cartridges - Cello, vdH, Benz, Zu, Hana - what stays and what goes?

Cello aka Miyabi Standard is exceptional cartridge and extremely rare, but your sample is refurbished with different cantilever (Ruby as you said). Who refurbished it for you? 

If you've got two very nice turntables and 5 cartridges, it behooves you to master the art of cartridge mounting.  Like MC says, it's not rocket science.  And if you don't do a perfect job, so what?  Many who think they do a perfect job probably don't, so you're in good company. The more you do it, the better you will be at doing it.  If you want to be as nutty as the rest of us, you need to be mounting your own cartridges for yourself.  MC is also correct, or at least I agree, when he says that hearing how two different cartridges sound in your own system, where you can go back and forth among several is per se very educational and gets you down the path of finding your own personal nirvana quite a bit faster than otherwise.

I’ll echo what others have said, with the components you have it’s in your best interest to learn how to mount a cartridge (easy) and setup a turntable (really not that hard). It’s not important what others think, what IS important is what sounds good to YOU.

Why sell? Need money? Planning demise?
Carts don’t last forever. Price retipping vs sales net for used.

Variety is spicy.

Ditto on diving in to learn cart setup. Same is true of the ET arm setup.

You have two turntables and one phono...thats a puzzle worth solving!

Are you using a standalone phono pre? There are options for dual input phono preamps. Some use a switch and some are dual preamps. Might look into them?