Battery is probably the single item on a motorcycle that have the most weight for its size. It would be logical to want to have a smaller battery that weigh less that OEM, if you want to increase thepower to weight ratio and improve fuel efficiency.
For a few years now, I've seen
Ballistic batteries usd by track riders to reduce the weight of their track bikes.
Battery technology have changed a bit, but if your bike is exposed to extrem tempartures from day to night, it would require maintenance regarles of type of battery.