Fits perfectly. Leaves full access to the side connectors on the 1DX2. Mounts in the right spot for the light bracket to be perfectly centered. I don't think there are any downsides to this bracket. Fits all my Arca Swiss tripod heads smoothly and with great fit.
I have used a Kirk bracket, which I like very much, but it does not offer the flexibility of the PMG bracket. The ability to attach the flash boomerang and the built in socket for the SS2 quick release wins the day. I have not had to extend the L side of the bracket, but it's nice to know I could if needed. My only request is that they would put an extra SS2 socket on the lower side of the bracket. I woulds also recommend they move the existing socket to the back corner away from the shutter. If you use a big SS2 quick release, it sits right where your hand wants to be during shooting. This of course can be quickly released, but if it was in the back corner, or side of the bracket it would not need to. The single strut supporting the side of the bracket is very strong so I did not notice any difference from it over one with two struts around the batter release area. For future, I also wouldn't mind seeing them add some of the features found on the R L bracket, such as ability to mount an accessory on that side and a cold shoe mount on top of the L.
The L-Bracket performs ist purpose well. All connections are easily accesible. To change the battery is no problem. I use my Wifi Tool WFT-E88 very often and this is now with my Bracket well protected.
Unbelievable quality. No adjustments needed at all . Fits like a glove and not feels bulky.