ORIGINAL: vbortone
I have the chance to try both configurations using same brand. I concluded that the 2-5S tends to last longer than a single 10S packs. It was not a rigorous measurement but I got that conclusion. There is some weight savings but is minimal.
And anecdotal evidence shows that it is usually one or the other of the outer two cells that fail in a 10s pack. Why, I don't know.