At least you don't need to worry about its not working due to it doing a dpf regeneration.
I find the stop start a lot more efficient in the summer. Through last winter mine hardly worked at all. If the state of the battery is too low it doesn't work yet I left my ignition on and ran the battery flat to a point it needed a jump. A 10 minute journey to my daughter's and then back again and the stop start worked and no way could the battery have been fully charged in that time. Or could it. It drives me nuts and all through winter I was thinking do I need to replace the battery. I guess one morning I will go to the car and it won't start and then I will know for sure.
I think they should rename the feature as "work or don't work".
Enjoy the car and there have been a couple of battery failures with cars as new as yours. Early warning signs are leave the car for a three days or so and it won't start. Don't let ford fob you off saying it needs a software update as chances are the battery is duff like a few others on here.