It's funny that I'm not even sure what you're talking about here. I replaced the 400 II's foot with the RRS foot that allows me to pop it into the RRS quick-release plates, such as the one on my monopod and tripod. I've had no issues with this type of replacement foot.
Cameras: 1DX, 1D4, 20D, 10D, S90, G2
Lenses: Canon 10-22mm, 16-35mm f2.8L II, 24-70mm f2.8L, 70-200mm f2.8L IS, 300mm f2.8L IS, 200mm f2L IS, 50mm f1.4, 50mm f1.2L, 85mm f1.2L, 1.4x TC, 2x TC, 500D macro, Zeiss 21mm
Lighting: 580EX, Elinchrom 600 RX's, D-Lite 4's, ABR800, 74" Eli Octa, 100cm/70cm DOs, Photoflex Medium Octa and reflectors, PW's, Lastolite Hilite, Newton Di400CR bracket