No L-bracket yet, but I'll be getting one for the 1D X. I do have a Wimberley P-5 plate on my 5DII (will go on the 7D), and P-20 lens plates on all my tripod collars, and all of those and the hand straps stay permanently attached. Since I frequently change from a standard lens to a big zoom on my 5DII, being able to quickly relocate the BR attachment point is very convenient (not a big deal on the 7D which I use almost exclusively with the 100-400).
I too have a Wimberley P-5 plate but it does not have a lug to put the hand strap through. How do you affix the Canon E1 strap and the P5 plate?
I also like being able to quickly remove the BR strap without leaving the lug behind, more comfortable for portrait grip with just a plate (or L-bracket) and I still have the handstrap to carry it more easily.
Do you un-screw the BR FastenR-3 from the underside of the P5 or do you use the Kirk 1" clamp like you mentioned earlier in the thread?
The photo below shows how I have been using my BR and L-bracket for over a year - super solid as the Ty-Rap has a metal locking pin inside. I love the setup and may try to loop the E1 onto the Ty-Rap too. I also really like the idea of the Kirk 1" clamp. Is this the one you use?http://www.bhphotovideo.com/c/product/555485-REG/Kirk_QRC_1_0_QRC_1_Quick_Release_Clamp.html