They should make one like the leather loop that the little nubs are just extra battery storage and they could wire them all together and have the band be the battery...
Not an every day thing, but I could see something like that for certain occasions. For example in 3 weeks I will be on vacation in Washington DC and hope to use the navigation on the watch a lot while walking around DC. And this is certainly a lot better price wise than the Reserve Strap.
Kind of like the battery case I have for my phone. Too bulky for every day use but I love having it on for a long day somewhere like Disneyland where I'm on the phone a lot killing time waiting in lines.
It's too early for me to trust anything that isn't approved by Apple. Perhaps by gen 2 when the watch has been out for awhile. I don't want to roast my watch especially not when it's sitting on my arm.