I think a valid concern is the longevity of the internal battery over time. Although, I have to believe that in the next 4-5 years something else will come on the market that will grab my attention. If such a device doesn't come out and I'm still using the A10, then I'll just have to have an adapter cable to run this in the field.
But...if this device is still is capable of running at 60% in 5 years, I'd still have 6+ hours of running time.
I get your point though.