Spacing is important.
Having games too close together can spoil the fun.
There is a great deal more involved with enhancing the pinball experience if you so choose.
Lighting and room acoustics are the 2 big ones.
That one "must have" will need room to breath, and if you love pinball as much as most of us do, you'l want to have space to cut loose
You have a wonderful collection and to be honest, unless you don't have to work and have a ton of spare time how would it be difficult to be satisfied with your existing line up ?
For home, I think 5-6 is a good number.
I run with 3 at the moment.
Looking to add 1 or 2 more, That's it.
Must have, I dunno yet.
The current rumors are lack lustre.
I'm pretty sad Venom didn't tick the "must have"
box for me, I really want an Eddy game.
Anyways, go for it, Do what turns you on !
Good luck !