Well I actively meditate quite often, but then I am used to being a "no one".
But I don't PvP much, and the main times I actively meditate are after I get rezzed and after I do a WoD dump to finish off a boss.
Anyway, that's interesting about the speed difference and good to know. I had been told it was the same passive rate. (Focus didn't exist yet when I played before, so it's a new skill to me.) I just went and looked it up on UO Guide and it turns out to all be quite complicated with INT and other things factored in. With 10 INT and 120 skill, Med seems to give about 47% faster passive regen, which is the highest difference possible from what I can tell. At 150 INT and the same skill level, Med only works about 26% faster. Significant but not overwhelming.
My mage runs 120 med, 120 focus, has 186 mana and 11 or 12 MR--yes, this is the guy I still actively meditate with. I think I have a mana addiction...