I'll just add my 2 pence worth (and that's probably all its worth)
I would go for the all over paint job. If you leave a line then it will only really serve as a good start point for the paint to flake away.
As for the finish, you will get a much better key if you use a course abrasive on the bumper, but personally I wouldn't try to rub down the bumper itself to a smooth finish. That's far too much like hard work. As I said abrade the surface, then apply a good quality filler primer and flatten that back to get your desired finish. This maye take more than one application to get it right. Just a tip here, if you flatten it back, then lightly dust it over with a black paint and lightly sand again, you'll spot any uneven surfaces and blemishes.
Last edited by Pat.w; 19th December 2007 at 05:17 PM.