Per Dave Platt:
There's a tradeoff. The low-self-discharge NiMH cells have a lower
capacity than "standard" ones of the same form-factor. I've seen
differences of 20-25% in practice. For high-quality AA cells,
the low-self-discharge ones I've bought tend to top out at
around 2000 mAh, while "standard" versions from the same manufacturer
run up to 2400-2500 or so.

So, if you tend to charge your NiMH cells and then use them
immediately (e.g. taking lots of photographs while on a trip) standard
cells are the way to go. For "standby" applications, low-self-
discharge cells work out better.

I guess the truly-obsessive could look at a chart of the self-discharge,
note where 20-25% happens, and then choose one or the other type battery
based on one's expectation of how long they will sit before use.

viz: http://www.stefanv.com/electronics/eneloop/graph.gif (from
http://www.stefanv.com/electronics/sanyo_eneloop.html)

Looks like the crossover point happens after about 20 days and the
regular ones need re-charging on a monthly basis to assure 50% capacity
when needed.
--
Pete Cresswell