So, now I have one.. Hope they are working well. I did get the 21 or 23 amp one.. Sorry, Sr moment.. So I'm hoping it's got enough power.. Did anyone buy the special charger/tender for it? Not sure how much that will be, but I want to get a long life out of a $200 battery.
The initial Shorai recommended for the 1150 GS was the 18 Ah, which I purchased. It was inadequate in temps below 35 degrees F. Shorai has since changed their recommendation for the 1150 to the 21 Ah battery. They replaced my original Shorai with a 21 Ah battery, but I've had a couple of bad breaks since installing it (ankle then 4 months later clavicle+5 ribs) and can't yet comment on cold weather starting.
I did purchase and do use the Shorai charger. Initially I would monitor my voltmeter and add the charger as the voltage approached 13, which would take about 4 weeks if the bike was not ridden. Because of my injuries and not riding for nearly a year I decided to leave the charger attached. I've found if the electrical power goes out once it is back on you have to hit the storage button on the charger, otherwise it sits with both the charge and storage lights illuminated.
Based on my experiences with the 18 Ah Shorai if I had it to do again I wouldn't purchase a lithium battery. If I either lived where the temps never got into the 30's or I never rode when the temps were below 40 degrees then lithium is definitely the way to go.