Imo 0.0001% is a small fee and let me discribe it with an example:
You send 10k GreenCredits to your friends wallet. The fee would be 0.00100000 GC in that case.
0.0005 GC go to the miners, the other 0.0005 GC will burned with the transaction.
Percentage fees are a bad idea because it costs people with lots of currency too much - the typical transaction (at least with bitcoin) is to send a payment to someone and the remaining balance somewhere else. If you maintain a high balance in any given account/transaction, you are constantly paying a percentage fee on it whenever you send money.
Also, for small transactions the fee is probably too small to prevent spam, although a small minimum fee fixes that.
It's like with the taxes. Big money should pay more fees than small money. A fix percentage is the modell!
How spam look like in this case?