Doing an experiment now with a Type 2 RMR. Mounted on a gun I shoot regularly, going on 1 year 8 months on the original battery. Going to see if it makes it to 2 years. Having a bottom mounted battery on an RMR is pretty much a moot point.
Just bought an SRO for my revolver. Looks like it will be a really big help finding the dot reliably when shooting weak hand only. As an aside, I enjoy people who shoot weak hand at matches. It's often their first experience doing so. Usual refrain, "Where the f**k is the dot?!?"