Will those 5 btc be enough though, considering this is a large campaign, and with higher rates than PD? Sure, there aren't that many users enrolled at the moment, but it should just be a matter of time until it gets full.

The following post should answer that question:
The OP and I have decided to check how many members have joined after a week and then calculate (based on assumptions) if we need to increase the escrowed amount. That should do for now.