Is there friction when a $100 student finds out that others are paying $20?
No. Everyone is aware of the sliding fee scale system and we all know that not everyone pays the same to train. No one cares about something so petty as who pays more than so-and-so. As for me I'm just happy to have more training partners on the mat.
As for how it affected revenue, I have no idea about that as I'm not privy to the financials but typically more members paying dues = more revenue.