If it's an alpha/beta or just a proof of concept then state that or you may have issues with public expectations.
If you plan on making a business around this project, might make some paths more difficult to take or lower the bar for competition.
# WARNING !! UNSTABLE WORK IN PROGRESS !! WARNING
At the top of my README.md if something isn't ready for public consumption.Other then that, I'm sure the other cautions that they bring up aren't as big of an issue.
You are basically ok in my book so long as you plop a copy-left license on it.
If you take the time to set the tone for the project you have more room to resist change requests that are in conflict with the vision.
If you think about doing it, make no mistakes and just do it from the start!
That is, if OP is really concerned about the $7. I don't think he is.
In other words, what features does it offer for early stage projects that Github, Atlassian, etc don't?