NiMH self-discharge is low enough to not matter for most applications. 5th generation Panasonic Eneloop is 90% after 1 year of storage, 80% after 3 years, 75% after 5 years, and 70% after 10 years.
Absolutely! However my baseline are my Li-ion 18650 cells which have those advantages as well, in addition to larger capacity. But I think I would be willing to give up the capacity if the price was much lower.
Yeah, considering the tradeoffs it has to be much cheaper to be worthwhile. I would say 5-7 euros per cell retail to be worth considering. Otherwise why bother ?