I tell ya, I'm hearing 100 different things about the MM metals. I even did my own small test and I THOUGHT it worked out well. I've read alot of stuff where people have said they've had no problems and others who have:
Don't primer before using it. It wasn't desinged for that.
You have to primer in order to get the surface smooth.
Primer with a gloss enamel only.
Primer with any kind you like.
Primer with a gloss laquer only.
Don't use the MM sealer because it degrades the finish.
Don't use Future because it degrades the finish.
Don't use Future becasue it's too glossy
I used Future in my test and it looked fine.
Use Future or MM sealer and you'll be able to mask over it.
You can use Future and/or sealer but don't masks or the tape will pull the sealer/Future and tape off.
Even with sealer the silver will still pull off (this is not true according to my test).
Don't prime. Paint your other colors, sand smooth, mask, then shoot the metal.
As you can tell, I don't know where to go. I really wanted to give it a try, but I think I'm just going to opt for using Alclad2.