That's funny. I just picked up the Insane Detail brush tonight. Planning to try it on my Stormtroopers.
Do yourself a favour and pick up a couple of Windsor and Newton Miniature Series 7 brushes, sizes 00, 0, and 1.
They're made from kalinsky sable, and are amazing brushes. They keep their tip if treated well, so no need for gimmicky brushes like the insane detail, which just don't hold enough paint.
I cannot stress enough how important it is to have great brushes. It makes a HUGE difference.