Huge fan of StackAid! Glad you're using it! Just to clarify and out of curiosity, what do you mean with "doesn't lock anything down" in the context of StackAid vs. Polar?

It doesn’t paywall anything, you can’t say that only people who support you on StackAid gets A or B.

(One idea I think we toyed with at Flattr, which was also a flat fee donation system, was to potentially enable people to lock something down on whether you donated to anything at all, but ultimately decided that the internet was meant to be opened and thus we added mechanisms to Flattr to make it really hard to abuse it as a paywall, which eg Germans loved but most Americans was really confused by )