I keep a couple boxes with all 6mm allen heads sizes, and nuts, 8mm's, lock and flat washers too.
Sometimes I reuse Phillips ( stock fasteners)when I feel like looking stock, between the cleaning and polishing, weeding out the damaged ones and not wanting to FK with impact drivers anymore, I like Allens better, as long as I keep them stocked. I can measure pressure with torque wrench. It makes life easier on me.
I don't enter my machines in shows, so I don't loose points for non original parts, I enjoy these machines for what they are, they make me happy, especially with Allens.