Regarding the Eneloop "miracle". IMHO, it looks like a consumer grade invention (e.g. for lazy and impatient). It's nice for long term storage probably (however, the alkalines shelf life is still better). But you sacrifice the capacity to have such a benefit (they have only 2000 mAh, you can get 2700 mAh and that's quite a noticeable difference. I've got 4 3800 mAh nonames, but didn't tested them yet, could be a hoax actually).
You are absolutely right. You do sacrifice some Amp-hour capacity when you choose a battery with a low self-discharge. This is because the low self-discharge property is created by using a much thicker dielectric inside compared to normal NiMH cell. That thicker dielectric, while keeping the stored electric charge from leaking across and balancing out, takes up some room normally used for the charge holding material, causing a slightly lower capacity.
It’s just a matter of weighing the properties of both against each other. Normal NiMH batteries will hold ~2700 mAh, but can empty themselves in a month. Low self-discharge NiMH batteries only hold ~2000 mAh, but can keep that charge solid for about a year.
Personally, I find the advantage of being able to store several thousand mAh of NiMH batteries that I know are still charged up trumps only having ~2700 mAh at one time because you need to wait for your next battery to charge before you get more. That is a simplified demonstration, of course, because you
can orchestrate your charging schedule to allow you to almost always have fully charged normal NiMH batteries, but that requires a lot more effort, and one of the premises of this forum is that the opportunities where batteries are a lifesaver doesn’t always work with our schedules.