The Optima batterys in several of the machines at work are over 10 years old and still work fine. I wont talk about it who it is YET but there is a battery thats coming out, with all the attributes of a typical AGM glass mat battery that will have 1.8 times the power to wieght ratio. A customer of ours is making them. The first prototypes hold 680amp load for 15seconds while holding 10vDC and have an RC of 120, all this in a 6lb package. Pricing however will blow most people away, easily in the 500+ range, but they have thier uses(like a race car thats already as light as possible).