EZ, if that primer you mentioned is a pale green color then it's bullet proof. That's some hard [censored]! I saw some that dried up in a mixing cup and then was removed from the cup. You can beat it against a metal desk and it doesn't chip or crack.
I'm using some HoK Epoxy primer now that I just found out is a California primer deal. It's doing a good job for me so far and dries up in 4-6 hours to where you can sand it. I then go in with some basecoat/clearcoat mud and do any shaping I need to do. I'm with Rex on the ability to feather out the bondo edges easier when it's on epoxy primer. No clue why it's like that, but when I use to apply bondo directly to the metal it left an edge most of the time that I could see after I spray on my primer. After all this I usually put on a Sealer, or another thin coat of EPoxy primer. hmmmmmm.....I really hate this subject & wish everything would come to my shop already primed and ready to paint! /ubbthreads/images/graemlins/tonofbricks.gif