I've done three repipes using the Uponor stuff with the expansion tool. I've used both brass and ep fittings and they seem to fit up the same. There's a lot to like about the system but a few glitchy things as well.
The type A PEX is noticeably better to work with than the regular HD stuff. Type B? It'll make a tighter turn without kinking and you'll find yourself using very few 90 elbows. There's a snap-in brace for corners that eliminates cutting and fitting an elbow in a particular location.
You have to plan the job ahead and order your parts accordingly. I don't think they're in stores yet, so if you need something and don't have it, it will slow things down for you. I tended to have leftover elbows, and could have used more 3/4x 1/2 fittings and m&f adapters.
The tool costs something over 400 dollars, but should be easy to sell when the job is done. My second repipe customer gave me the tool and leftover fittings when I called him up later on to see if he would lend/sell it to me.
A prince he was. My kind of customer.
One other thing comes to mind. Since you'll likely be running pipes in the attic, rodents love to chew this stuff. Had to do a bunch of repairs in the last house I lived in on account of that.
