I currently have a Emmo Zone 72v/20ah Lead Acid. I was thinking of going to a 72v/20ah lithium. The question I'd like to ask is, would a 72v/20ah be a significant improvement over a 72v/20ah Lead Acid? Should I go with the 72v/20ah lithium or go to a higher rating like a 72v/40ah? I am open to...