Here are some discharge test data for Energizer 2100 cells. Note Sanyo makes the Energizer 2100 cells and both are identical.
It is quite possible to make a battery meter that functions properly with NiMH. It's not even that hard. What's more, it's not particularly difficult to design a circuit that understands what type of cells are connected. There are many examples of universal chargers that can identify alkaline, NiMH, NiCd, LiIon, and lithium polymer. The only types of cells that I don't believe are possible to distinguish are alkaline and rechargeable alkaline. The characteristics are too close.
I will also point out that the lower internal resistance of NiMH over Alkaline has two particular characteristics that are worthy of note here. One, NiMH can output significantly more current than Alkaline batteries and they are happy to do so. Under load, NiMH will not sag nearly as much. I have no doubt, when the camera is operating, healthy NiMH cells maintain more voltage than Alkaline. Any testing I've done has proven this out. Second, the low internal resistance of NiMH causes them to go flat over time, regardless of load. Even just sitting on the shelf, an NiMH cell will be nearly useless after 45 days without a fresh charge.
I use Energizer 2500 cells purchased from the grocery store in my K100D. Sanyo makes these cells for Energizer and they are very good. Higher rated cells are made by Energizer themselves. I understand the higher rated cells are good also but I can't buy them at the grocery store for $14 CDN for 4 cells.
My battery indicator shows full. I've taken about 400 so far (50, or so with flash). I'll post up when I know how long these cells last.
How many shots do we need from a set of cells? Seriously?
Oh... and the La Crosse BC-900 chargers are nothing short of marvelous. There is no better consumer grade charger, for the money. I prefer firmware 0.32 to 0.33 as 0.33 has lower thermal runaway threshold which causes the charge to cycle. Always have a s small fan blowing over the BC-900 when it's charging. At any setting over 500mA, the cells can overheat and melt down.