Different sources/types of Micarta seem to finish differently. I have had some black linen, and black canvas that looked very nice, and gelt good, just wet sanded to 240 grit. The green canvas stuff that I bought was a pig to finish by comparison and had to be sanded down to 400-600 before it started to look alright.
I shape with files, then wet sand to keep the dust down. Think about a good dust mask because unlike wood, even the dust you get from a fairly coarse file will become airborne readily. It doesn't smell particularly nice, hence doing my sanding wet.
A nice finish can be achieved with Webrax / Scothbrite abrasive pads, they will tend to cut away the exposed cloth fibres faster than the phenolic resin so you get a subtle texture.
Hope you don't mind me butting in Stu