After having used my e-bike for a year now, I just can't see anyone using anything less than about a 15 AH battery. By the time I get out of my neighborhood and to where I want to go, I've already used 5 AH of battery. Then I use about 3 AH enjoying the ride and sight seeing, then it's time to get back which uses another 4 - 5 AH. I just don't see how anyone can be happy with a 10 AH or less battery.
BTW, I'm talking about Lithium batteries. For SLA, it would be even more. I light sight seeing though. I like enjoying a good bike ride. Everything is perfect on a bike ride for me. On a bike ride, there are no problems, no financial problems, no personal problems, just me and the bike and the road.