IMHO, I would stay with the 5%. I have seen some guys use minoxidil based products above 5% and some experience massive shedding from it. To my understanding, the FDA has approved only 2% and 5% for treating hairloss.
NOTE: I am not a physician and not employed by any doctor/clinic. My opinions are not medical advice nor are they the opinions of the following endorsing physicians: Dr. Bob True & Dr. Bob Dorin