Yes Hu C is the way to go as that is what I am using. I ride regularly in City limits for about 1 year now, and was stopped at a breathalyzer road block they said you have Hu C and I said Yes I'm just passing through. Other times I am just ignored.

I have had a couple gas station ladies refuse to add gas for me, but I just went to a different person AT the SAME gas station and they will do it.

Also I hear the 1st registration has to be in Shanghai as new to get a registration in shanghai. Also you can't change a Hu A to a Hu C or viceversa... pain in the ass..