I think our home is about to become the adoptee of an antique treadle sewing machine. Should I try using it, even repairing it, etc. or just not touch it?

Personally I would clean her up and do whatever it takes to get her sewing. Could you post a pic of her?
I have 2, one my granny sewed on for 65 yrs and a red eye I need a cabinet for.

Use it, use it! It's fun!

Treadling is so much fun! I think I am more addicted to the fixing up of them, though.

I'm refinishing a cabinet, then I'll clean the machine I bought. I hope I can use it when I'm done.

Clean it up and use it!

Use it! Would love one!!

I'd say use it as well. We're just starting to use ours but I've already had more pure fun sewing on it than I've ever had before (though I haven't started doing actual projects on it yet.) The sense of connection and the level of control give me a level of confidence that I've never had with another machine (this doesn't apply to my wife, however!)

The other thing that I really enjoy is the rhythm. With an electric machine you start, stop, slow down, etc... instantly. That's fine but it feels somewhat herky-jerky to me. The treadle, on the other hand, rewards a steadier, more uniform pace - slowing and speeding up are OK but you don't want to let it stop - it's typically more than just a push of the foot to start up again - and it's easy to have it stop on you if you're going slowly and you aren't steady.

I love mine-they are practically indestructable! So-go for it!

One other note. For me, at least, the treadle machine has been far less frustrating. The tension adjustment on every other machine I've tried has been finicky (at best), but on the 9W it's been dead simple and very repeatable.