My experience is that they don't compare to basic copper-top Duracells in either strength of initial charge/recharge or longevity.
Not surprising since the nominal output voltage of an Alkaline battery is 1.5V while that of NiCd and NiMH batteries is 1.2v (or 1.25v if they are Mil Spec). Note that the output voltage of NiMH is relatively flat until the battery is very nearly empty while the output of alkaline and NiCd lowers at a relatively constant rate throughout the discharge cycle.
They are a hell of a lot less costly to run, though.
Less costly yes, but not as much less than one might think after factoring in the cost of the charger and the electricity to run the charger. In my case I also factor in the aggravation of having to replace the batteries so often. Murphy's law applies to battery failure too.
