I measured the capacity of my new pack when I got it with my R/C battery charger and got 4100 mAh or so. Now, the pack was officially rated at 4400 mAh I think, and the old packs were similarly rated, so while that does seem a bit low (good quality new batteries usually measure slightly over their rated capacity) it was pretty close, and sometimes batteries do better on their second cycling.

I haven't really used the light much, but at least as far as my measurement went ... the capacity was at least 90% of what it should be.