Same here with my Slice and a pair of Hohm Grown's, the battery will be full coming off of the Xtar SV2. It will show 100% on the slice and a half dozen pulls later at 65W, it's in the 90's. If you leave it the meter will slowly creep its way back up. I occasionally charge the battery in the Slice, but I really like the 2A speed on the Xtar for the Hohm Grown's and the LUX's iJoy's.
I have a Brillipower 26650 in my VT75, it's one of the highest rated on mooch's list and it works the same way. Starts out with the meter dropping fast then levels out. My VT75 had the Battery Analyzer run on that battery, so the meter on it is tuned to the Brillipower.
I can't give you any battery run time specs since I carry 4 or 5 rigs with me daily (flavor ADHD
) and charge them before they are even half depleted.