If you’re able to go test drive some at shows then by all means do so. I would get the biggest and best you can now so you don’t have to deal with it later. It is a lot of work to take down, move and level etc..., unless of course someone else does it for you. And yes, they take up room, I have a HQ Fusion on a 12ft gallery frame and it comfortably fits in a area 10.5w x 17L in my basement and I am able to work very comfortably.
As far a loading a quilt, once you find what works best for you it doesn’t are that long, I pin my backs to the leaders and I float my tops so it only takes me perhaps 30 minutes to load my backing.
Let us know what you decide to get, you’re going to love it!