I've used .005 a bit and both marking pens and India ink. The india ink seems to take a LONG time to dry but it's very good on the black rubber window trim of newer style cars.
I've also gone to a number of different color pens / markers for all kinds of things I used to go cross eyed trying to paint with a brush. Gauge highlights, molded in wires, body badges... It seems there are alot more colors now than a few years ago and tips sizes small enough to use for details. Spend some time in marker isle at Hobby Lobby of your LHS and you'll be amazed.
Dave