I really love the SMH-10R. It's small, lightweight, easy to use (even with normal riding gloves), etc. etc. etc.
But why is the battery so small. It's externally mounted, a larger battery option wouldn't be a problem at all. I'd buy one with 12 hour talk time life immediately. Mine ran out at 8 hours or so fairly reliably on a recent 9 day trip. 12 hours would have been perfect. If it's never going to be available, I'm thinking about paralleling two SMH-10R Batteries on the back of my helmet and never have to worry about running out of battery.