I'm doing one now. I question the logic of it, but it's my only option. It's the second floor of the garage.
It's been slow going getting set up. As I get heavy things, I dismantle them and take them up the stairs with others. I've debated putting a chain hoist in so I can move some stuff just with my girlfriend. Structural integrity has been on my mind a lot with it. For example, I got an old super solid contractor saw I'll build a cabinet around instead of a nice unisaw. A few hundred pounds here and there will add up fast. No floor bounce yet, and I've got most stuff up there already. It was built pretty solid.
One bonus...It's really allowed me to true up all the sort of junky old stuff I bought to give woodworking a try.
The floor up there is 25x25 with 7 foot ceilings.
I will say, part of what gave me the bravery to try this me a big city locksmith brother in law. He moves giant safes all the time...I'm not talking gun safes here. Huge, huge ones. He's got all kinds of fancy gizmos to move things up and down stairs. I haven't had to call him yet, but I might with a planer. I'm thinking when we move I'll just hire a rigging company for a day to get everything on the first floor. I'm not planning to move with any of the big tools.
As far as finished projects, that floor has a window that opens to 4 foot by 5 foot. I've never seen one that big. If I decide to do anything that huge I have to do up there, I'll just drop it down through there. My plan is to do assembly of large items on the first floor of the garage. I'm also planning on making anything I want to move with later so I can disassemble it easily. It's not actual woodworking, but the reloading bench I put in the basement is pretty interesting in that way.
I probably wouldn't be doing this if we were going to live in this house or the town we live in forever. We'll only be here around 10 years.
For materials, I can get 12 foot boards up the stairs no problem. The guy made the steps so they ride in the corner and have a turn. I took the upstairs railing out....I would not have done that if we had kids. I haven't tried a sheet of plywood yet, but I'm sure I won't have a problem. If I would, I'm getting a track saw anyway.
My main worry is dust collection. I have no idea what I'm going with that yet. I don't want everything downstairs covered in sawdust permanently. I am going to put a commercial exhaust fan in the vent up there. It gets HOT. Our house is kind of on top of a hill above all the others and I worry about showering the neighbor's backyards with sawdust, but I'll just have to see.