You can use an 11/7 BUT the plane will be faster, and at higher speed it will be more sensitive to control input, and last but absolutely not least she may have a more difficult time landing. Trainers kind of float anyway with more thrust at idle you may find yourself forcing it down, and that is no fun.

I went from a 12/6 to a 13/6 on my hobbistar 60 and landing is now an event lol she comes in a little hotter