rustoleum takes FOREVER to cure, but it's a tougher finished product. seems like it can take anywhere from 3-6 weeks before its really good and cured, and thats sitting in front of a good space heater in my shop. krylon, by contrast, is generally ready for action in 15 minutes with a light coat, or a few hours at the most, for thick/multiple coats. so i really only use rustoleum for magazines anymore, and krylong for guns. it also seems to depend a little on the color, but i dont keep track of which does what.
rustoleums got a lot better color selection, but im not too picky about camo colors- the krylon khaki is really light, as you said, so i just "mist" the gun to get some color splotchiness. doesn't get nearly so light that way.
so it's a trade-off... rustoleum definately comes in a lot more camo-compatible colors and holds up better, but it puts your weapon out of action for a long time. way longer than i have patience for.
here's one i did not too long ago in krylon... the stock was already "coyote" and the VFG was OD or FG.. the rail was DD's poop colored version of "FDE." i dont remember what color the battlegrip was. black, i think.
l_dd81cb6ba7be4ca5b5412b57080a55d2.jpg
also, keep in mind- the rustoleum satin paint is still fairly glossy.. in fact, i did some mags recently in forest green that almost seemed like they were high-gloss. a really fine, light sanding will fix that, but you also lose some tuffness by sanding- does a few months worth of wear in one fell swoop.
hope that helps