I'm used with Manfrotto's QR2 release system and I find it really quick when I need to detach the camera from the tripod and shot hand-held. I do this rather often when I alternate long-exposure shots with normal, photojournalism shots (at a wedding for example).
OTOH, I'm looking at Arca Swiss type of plates but I think that these are more slow in operation because one needs to (un)tighten a knob in order to (un)lock the camera which is slower and, also, is much prone to human errors (wh/if I don't turn enough the knob in order to keep the camera firmly in place?). I found that there are RRS lever clamps but AFAIS are rather expensive, more complicated to use and also the ball should support them.
What do you think?