until prices come down on alternative batteries types, i keep coming back to Deka AGM for the price. I find these last for 4-5 years with no issues and no maintenance needed. They are 1/2 the price of the new technology batteries and so unless these new batteries last 9-10yrs (an i doubt that) the cost benefit is not there.
Yes they weigh a few pounds less so only in light 250 thumpers would it be noticed. On heavy dual-sports and adv bikes the only thing lighter feeling is your wallet.