The million that people talk about are actually in dog hours, so multiply by 7 ...
All good points made above about the time trade-offs, etc.; and of course as you get more experience with whichever unit you select you will streamline the processes. The bottom line is a diligent diver (OC or otherwise) would have already been spending X amount of time prepping/checking his or her kit. One who isn't in that category probably shouldn't be considering a Rebreather in the first place ... JMHO.