Any word on their content limitations? With the recent kerfluffel between Patreon and adult content creators, is this an alternative? I'm going to guess not, given the association with Visa and MC only.

... Had to dig - nope:

> Pornographic or highly suggestive content or images that violate the applicable laws.

Their "Types of websites not permitted" list is fairly long: https://flattr.com/files/terms.pdf