Our standard battery is a sealed lead acid unit normally used for motorcycles and personal watercraft. As Bob points out it was selected for its light weight yet still reasonable capacity. No question there is no surplus of power there however. Unfortunately we can't seem to find an AGM/RG battery (such as an Odyssey) in the same size otherwise that might make a good upgrade.
Personally, I'd replace the battery in my Carbon Cub every other year during the annual just as a proactive preventative measure as batteries do degrade over time. Also, though I can't/won't announce anything at this time, we have several electrical system tweaks in development.