This is Contenture, with an extra barrier to conversion for each micropayment (clicking the Flattr button). It has every issue that makes Contenture a bad idea, squared. See here: http://news.ycombinator.com/item?id=607937
http://news.ycombinator.com/item?id=627679
Obviously, Contenture got it wrong. I agree Flattr's required-clicks are wrong, too.
I only heard about Kachingle and Sprinklepenny via this thread. Kachingle's limited-info flash-intro isn't confidence-inspiring. Sprinklepenny seems to understand more of what could appeal to readers (reallocate/retract funds) and publishers (detailed reporting).
But I don't see any reference to creating a gradient to reward subscribers -- for example skipping a Salon-style interstitial -- and extra rewards for the sites that get people signed up. That's likely the key problem to solve to bootstrap a self-reinforcing cycle of site and reader enrollment.