We use the gray water bypass in our sani-con. It works ok, but won't keep up with multiple showers in a row. I take mine first, then go outside and switch on the pump while DW is in shower, otherwise she's ankle deep and hollering.
Kinda off the subject, but I am considering getting a water pump type controller for it, momentary switches, and putting a second swith inside the bus in the main panel, that way if I forget something it's an easy matter to turn the pump on, and on the MANY times I've walked away and forgot the pump was on, easier to turn it off.
On the "be careful what goes down the toilet" comment, I mentioned above that Monaco uses BOTH the sanicon and the Techma Electric macerating toilet.
I am firmly convinced it is the combination that works so well for us.
Nothing solid ever goes into our black tank. It's all ground to slush at the source.
Downside is the Techma uses a lot of water. Even setting the bowl level as small as will cover the trap, we always fill the black tank before the gray.
On Nascar race weekends, rule is "guys pee in the porta potties"
and "only flush the toilet after 4 girl P's"
Doing that, we can get 4 days for 5 people.