Collinite 845 works amazingly well. I wasn't able to hand wash my car at all this past winter, and we had huge snows with lots of salt and chemicals on the road. When the weather finally broke and I started washing my wheels, I couldn't believe nothing stuck to them. They were easy to clean up and looked like new.
So, in my opinion, there's no real need for a "wheel sealant". However, I do plan to try GTechniq's wheel armour in the future just to see how it compares.