My 8 yr old machine doesn't have it. So I don't know how much difference it makes
I don't see any harm having it. More future proof. But then you lose the clear door.
There is also difference in depth
Z2m is 55cm depth with 1200 rpm
Z5m is 47cm depth. But the drum diameter is larger. So volume wise both are equivalent
Z5m has a better looking UI with 1400 rpm
Why are you considering front loaders now when your opener said you ruled them out?