I don't know that you can definitely say that lithium are "better" than NiMH - it depends upon the application. I will put lithium primaries in items that are going to be used infrequently and stored for potentially long periods of time - also where cold weather is anticipated or weight is really critical. Eneloops for just about everything else. They will save you a lot of money and cut down on your environmental footprint.
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Geezer in Chief