I don't know if Adriaan Tijsseling is the brains behind kula, but it's good bet since they seem to be the home of ecto and 1001.
In any event endo looks like a worthy competitor to NetNewsWire, which is the best of the RSS aggregators I've used. I'm really interested in the extensibility features. A clean, full-featured plug-in architecture combined with good AppleScript support means a wide latitude for experimentation. And the feed management tools look like a nice departure from the current "three pane/river of news" dichotomy.
endo's probably worth shelling out $18.00, at least if you're on a Mac.