I don’t think the data supports your claim about sharper, and low-light performance. AFAIK the best low-light performance in the world is the Sony A7S, which is

I don’t think the data supports your claim about sharper, and low-light performance. AFAIK the best low-light performance in the world is the Sony A7S, which is mirrorless. At the high end, I don’t think either of the mirrorless or SLR choices are significantly sharper than each other. SLRs have been quicker but that advantage is diminishing fast. However, you're right about batteries, I use a Fuji XT-1 and carry a couple of spare aftermarket batteries around in my camera bag. Which isn't a problem, I find. Lots of pros are going mirrorless.