InjectedCutty,
I was faced with the same decision just a couple months ago. I did the same research and compared the same brands. My conclusion was that one will not go wrong with any of the pure lead AGMs. Since Miss Elsie is not a daily driver, your concern over speed of replacement was not a factor in my decision process. I ordered an Odyssey from Summit. As it has only been about 2 - to three months, I can't give you any long-term insights, but I can say it seems to stay strong longer than my old battery when cranking during those first starts after the fuel has evaporated out of the carb.