I was using the Stewart Systems EkoPrime water based primer for my tail section. It worked pretty well, easy cleanup with water and it shot fairly easily. I liked the white color too. The problem I have with it is it isn't that durable. That may be because I'm always trying to assemble the parts right away but that's the way it is. So I'm planning on changing to an epoxy primer for my wings.
I've been looking at the DP epoxy primer and the mainstay AKZO epoxy primer. From what I've read the AKZO primer seems to be the best for what we are doing. I was trying to aviod the Alodine step in the prep process but I think I',m going to start doing the Alodine and see how it goes. I was reading the DP documentation and it says it requires a self etching primer base. That is just too many steps for me, but again I wanted the white color. The other downside of the AKZO is you have to buy two gallons at once. That isn't that big of a deal I guess just bite the bullet since it is cheaper than the DP primer. So, I'm probably going to go with AKZO from now on.
Just my two cents.