Don't apologize for using metric. Us stupid Yanks are still obsessed with this abstract and outdated measuring system, which requires extensive memorization.
I'd switch to metric if I could.... Not that my mind won't, it's just that everone around me won't.
Jingles brings up a good point about the tri-LED. It has less RGB blur/bleed. I see this problem with my Color Fusions since they use 3 bulbs, each with a different filter, to do RGB mixing, and while it's decent, it isn't great.
(Yes, the Color Fusion is an ADJ fixture)