The 15% march attrition is adjusted by certain things.
First, a minimum of 3000+(300* morale) suffers NO attrition. (The rulebook is wrong we found out in another thread).
Second, roads, moving into friendly provinces, etc., do also.
That being said, I don't mind a reduction. Did you have a specific level in mind? (10%, maybe?) (don't have the rules in front of me so don't know what that would be)?
At 10%, for a 10,000 man division (5.0 morale) marching on roads in a friendly province, that would be a marching loss of 290 men. (Assuming my calculations are correct).
Thoughts everyone else?