I really don't see much of a comparison here..one is a very small luxury cruise ship.should be very nice and very quiet..the other is an enclave on a giant ship with lots of things to see and do outside of YC...
I would take the YC experience most every time...
Regent and Silversea, not that might be a decent comparison, but has no place here.
Oh and I'm 60, never had any issues with kids on my 3 YC cruises. Have another one booked January of 25.