I dubbed my first birds a couple months ago with an experienced breeder helping me out. It wasn't as bad as I thought it would be. I was expecting the birds to freak out, but they didn't. I was expecting a lot of head shaking and other indications of pain, but they just went about their business.
OEGB would be better than MGB because you don't trim the comb as close to the head. I would definately do it in cooler weather when there aren't flies around. The breeder I worked with tries to do it right before they molt so the hackle feathers aren't stained.
I've heard you can numb the comb/wattles with a little Ambesol, but haven't tried it. If you use a styptic powder, make sure it won't hurt their eyes. The breeder sugggested using plain flour. I've used Cream of Tartar on horses, and that works too.
Not something I look forward to, but can do.