I've never used flash and never felt that I had to have it. I use IR, SW, FF, Provoke, and Convalescence. Mostly use SW while zerk and IR are up, not because they are amazing but because I've never felt that I needed flash. True the bonus of Flash being MP based is nice, but I've really only had issues with Relic+1 dps when it comes to threat.

Given of course, my opinions are apparently moot since i've not been in turn 1 yet.