Personaly, I use dipping when I have a lot of figures to do. I used it to make Donjon and dragon Wrath of ashardalon 40 figures.
I'm using acrylic wood stain, "middle oak". It dries in about half an hour, and don't smell too much. I can "fix" the effect using a hair dryer if I want.
Dipping is a cool way to make regiments, armies or big tabletop board games boxes ( doom, descent, lord of the ring, dungeon and dragons, etc... that kind of games with dozens of plastic figures). Of course the best way is to mix it with standard tabletop painting technics (black lining, drybrush, washes).
Here's a little before/after :







Congrats for the 15mm scifi squads, they look marvellous !