I think revolvers work great....if you have open diffs. With lockers, you can get some mean axle wrap.
I had them front and rear with open diffs and they worked great. Lots of flex (if you match them to longer shocks, etc.) But once I got a rear locker, the rear revolvers gave me all sorts of headaches as the rear end would hop and traction would suck.
Now, I still have revolvers up front (open) and they still work great as I have modified shock towers and longer brake lines...
In terms of why they are upside down, I'm not sure. The front and rear revolvers are different. The fronts have a different geometry to clear the power steering unit. The two halves are asymmetric, whereas the rears look more symmetric.
Hope that helps!