My experience to date with graphite and epoxy has been applying it to bow & stern rub strips, greenland paddle blade tips, and the bottom of my RC sailboat. All these jobs required small quantities and I applied it with foam brushes. It went on ok, but the application was not the best. I had taken note of recomendations to use a short knap foam roller, but it did not seem applicable to my small projects. Today, after having sanded off the old varnish, I applied the graphite/epoxy mix to the bottom of my MC 16.5 using a foam roller. The ease of application was beyond amazing. A nice even distrubution and no dribbles at the chine. I used Laszlo's recommendation to pour some on and go at it with the roller. Some tipping out was necessary with a foam brush to get bubbles out, but overall I am floored at nicely it went on. It will cure tonight and get a second coat tomorrow.
By the way, for those who have wondered about quantity, I used 12 pumps each of epoxy and hardner mixed with an almost equal quantity of graphite (add liquid to powder, not the other way around). This is the max you can mix up in a 9oz plastic drink cup without it running all down the outside. It was a good amount to do the bottom plus 1" above the lower chine. (may have gotten by with 1 pump less)
Hope all these comments and tips are helpful out there.