My personal lumen sweetspots are 0.3 lms and ~ 3 lms from a floody XML from my Quark or D25A - as a camper I probably spend 40/40% of my time at these levels - my low and medium with night adapted eyes. The 0.3 level is a bright moonlight mode (can be blinding waking from sleep) but I find it the perfect book reading level, and therefore also find it fine for most close task work with my hands, esp. from when aimed from a headband or my DIY neckband. I'm runtime freak and like the ~ 200 hrs per AA capability, and between that and a ~50 hr / 3 lms mode, a single AA cell will last me any easy week's camping trip or Hurricane Sandy power outage, and I could easily live on only these 2 modes.
My L10 N219 4 mode has a 0.04 lm mode, which I find too low for most anything, except in home navigation with completely night adapted eyes - I didn't like having to cycle past it everytime. I got the 3 mode next and measure low to be 2.5 lms... I could do with lower, but anything in the 1-5 lumen range is fine by me... your eyes will adjust for close range task work and it's just a matter of runtime after that.
Speaking of runtime, I'm actually doing a side-by-side test with a Foursevens Mini AA HCRI (also measures 2.5 lms) with ~1750mah Eneloops (measure on a Maha C9000). The 47s quit @ ~22 hrs.... yesterday... the L10 is still going at 46 hrs.... I'm impressed. You cannot beat the tint of the N219, but I have to say that I'm not a fan of its foam spring/battery spacer.