This bird can turn some, so surprise those that mistake it for one of the 109's that can't turn so well. Learn to shoot very well, and only take the good shots, as it doesn't have a great gun set.
Franz is a nice plane, but you must be a good gunner, and you'll have to kill them all to escape. Your only way out of a bad situation most of the time is to kill all the bad guys or out-climb them.
Bottom line is you need very good SA and maintain an E advantage. A higher Spit is bad bad trouble for the Franz. Keep your eyes peeled, and don't miss.