I think you are correct about the quota system being highly requested and yes it is a point of difference.I am working furiously on 1.0 though. There's so much I want to do and so little time.. so it seems inevitable some features will get cut. I'm trying to make it as good as possible though, focusing a lot of my effort on improving the quota system since it seems a lot of people like that feature and no other firmware has it.
I've been thinking how you can generate a little income while still keeping to the open source principles.
I think you should consider creating a quota management system for the ROBIN project. The difference between gargoyle and ROBIN is ROBIN members are trying to generate income as WISP's while Gargoyle users i suspect are home users managing their bandwidth. WISP's require support and i think this is where you could generate income.
To do this i think you need a more powerful router. I would suggest ubiquiti Powerstation.
Performance Featuring a fast 680MHz MIPS 24K CPU, 64MB RAM, and 16MB Flash; RouterStation provides a excellent horsepower for a variety of processor intensive multi-radio system applications.
You could keep download free and open source but charge say $10 to be able to view the forum and maybe $50 a year to be able to add messages to the forum. If you are an WISP and want premium support you could charge $25 a month.
Just my thoughts
Don't tell my wife but i made a donation and i don't even use gargoyle