I now have significant operation on the Batteries plus X2-14. My Carbon cub has the original battery box and the original starter. It has always started strong with no delay at the compression stroke. In fact, one hot day here in Florida, after a fuel stop with engine hot, I decided to shut down after the start to check the fuel caps.
Got back into the plane with no delay and it spun up beautifully. That is a worst case scenario.
By the way, they provide a 24 month replacement warranty with no prorating.
Now if I can just be sure to land near a Batteries Plus dealer. Barring that I like Gary's approach of carrying a Lithium Iron spare.
regards, Carl