Complex is better than simple. A simple system can easily be abused, while a complex one will have little to no loop holes, and the holes it does have can easily be filled quickly. To be blunt - Do /not/ allow exchanging pixels for joules. Your economy is going to bust immediately when future Donald Trump comes in with bags of pixels and starts making a monopoly out of your colony. If you're going to use a currency for your colony only, I would advise making it so it has to be earned at said colony. People could sell weapons or other equipment /for/ Jules. Something like that would sound a lot better than exchanging pixels for them.
Considering Im going to be renting out buildings for shop owners, this could be done quite efficiently. not to mention I have stalls set up as mini shops. And you have a good point with a complex system.
