I'm skeptical about the way the MOS is calculated. Playing by the book, the lower you roll, the bigger your MOS is. The problem is that it implies to do a subtraction to calculate the MOS. It isn't hard in itself, but it can be annoying.
So, here is my suggestion : on your D100, the MOS is the tens digit. Result :
- you have to roll just below the TN to get the best MOS
- you read the MOS *instantly*
- you have to do a subtraction only if you want to calculate a Margin of Failure, and it is "9-tens digit"
What do you think ? As I didn't read the rules in deep details, is there a rule somewhere that wouldn't work with this ?