I have the B-85B Portrait Perfect package from RRS, and I am extremely pleased with it. And it does not interfere at all with my left hand being able to hold the lens barrel or rotate the zoom or focus rings of my 17-55 IS, 85 1.8, 60 2.8, or 70-200 f/4L IS. Don't be scared off by that mis-conception.
Having the BH-40 LR II ballhead on top of my tripod is also nice, as I can put the camera on the tripod and use the flash bracket without any issues. I can also plug in the remote shutter cord and it all works together very seamlessly. Nice for doing home studio work strobist-style.
I also have the FA-EX1 extender when I really want the over-the-camera-lens flash to be coming down at an angle, and I also have the MPR-CL II rail which works well when trying to get the lens nodal point over the rotating center of my ballhead when doing panoramas.
I've heard good things about the Newton and Custom Brackets systems as well, so I'm sure you can't go wrong either way.
Regards.
