I'd recommend 53-55 as the top end, based on my experience.
My cooler is set at 48 which usually gives me a fermentation temp of 52-53 with lager yeast.
Okay, second brew with this yeast is a Munich Dunkel, same process, same temps. This one is absolutely gorgeous, clean, malty and bright.Certainly a darker beer is going to be more forgiving than the Maibock, but I can't see anything wrong with it. Now, I guess I have to give the Maibock some more time to mature and then make my final judgement, but if I were just going on the dunkel, I would recommend it highly and use it again.