I consider my Prius to be pretty darned spacious. I'm pretty tall and yet if I set the front seats so I fit in them there's still enough leg room for back seat passengers. Headroom is excellent. As for the capacity to haul stuff, I suspect that it would be comparable to the 9-5 given that they taper similarly toward the rear. The 9-5 might have an edge when it comes to length.

This is a great time to buy a Prius since you can find them on dealer lots in large numbers, so I would suggest having a look for yourself.