Around 4 years ago Amazon had a good deal on Delco batteries... like under $30 good. So I bought one and put it on the shelf for a couple years. After 8 years I started getting cold feet and removed the working stock battery and installed the Delco. Starting my 3rd year on that - after sitting for about 4 months the Wing fired right up last Saturday. I do not even own a trickle charger/maintainer.
I'd say your stock battery has plenty of life left. You gamble with new ones too.