If I had some smaller website that I charge nothing or barely anything on, I might. If I had a bigger SaaS product, probably not. I wouldn't say your pricing is necessarily unfair, but paying 5% for what is probably a very small part of the application, I couldn't stomach.
Thanks for the feedback! I’m open to changing the fee – is there a % fee you would be more comfortable with?
As an alternative to a fixed percent, I'd feel a lot better about a model where the fee gets progressively less with a larger amount of users. This may or may not be a personal thing.