I have been using a sloop sail and I have the boat pretty powered up...
37mm of spreader rake
32/500lbs on the diamonds.
At Sprinfever on the first day of racing when there was a little more than 10kts, I tightened by diamonds close to 35, in lbs I don't know what that is, but there were couple of times I had to come off of the wire on the first race cause I was way too depowered with that setting. I was sheeting in as hard as possible and that made it worse. I also didn't do well in that race. After that race, I loosened my diamonds back to about 32 and the boat had more power and I could trap the whole time going upwind. I also did better in that race. I might have been back in the pack, but I wasn't that far behind at all.
I do have stiffer battens up top, but from that regatta, I don't think it's that hard to depower the Sloop main for a UNI rig. Of course, that's up to a certain extant anyway. After 15kts, you need less sail area on a UNI rig to be almost as fast as the sloops.
At least that's my opinion anyway.
So don't SHOOT ME!

Mike