I've used implement paint on both my dad's and my trucks, and they looked completely serviceable. The brand I used was Forrest Paint, it was pretty dull without being flat, but for work trucks, there's not a tear shed when a rusty scrap of metal scrapes a stripe down the side. Price was about 1/10 the cost of automotive paint, and it seems much more durable. I can't comment on using a brush or roller, since I always shoot paint with a gun. The colors available were mostly safety colors (fire red, road yellow, plus a couple of blues and greens) so, again, totally serviceable, but not at all flashy.
