Sikuli is simple but from what I know about it you can't write maintainable tests with it. Relying on the pictures to be always the same and driving your test is guaranteed to cause false positives.
I think the future lies with platforms like Screenster that have recording, collaboration, built-in browser execution, visual verification and lots of other magic, and not with low-level frameworks like Sikuli.
Screenster support for timeouts is much more extensive. It automatically determines the time it takes for the server to process each user action, it uses the visual baseline to wait for the right state instead of timing out or waiting too long.
Obviously you can do everything with WebDriver, Screenster uses it too. The point is that you can get a lot of benefits out of the box when you are using a highler level platform like Screenster vs hand coding to a low level API like WebDriver.
I think "doing more harm than good" came from a different post... I don't see anything wrong with comparing an open source and commercial product. We'd still be using IRC if Slack didn't come around.
Time is not free so in the end you have to compare the total cost and productivity and choose the best tool for yourself.
I think the future lies with platforms like Screenster that have recording, collaboration, built-in browser execution, visual verification and lots of other magic, and not with low-level frameworks like Sikuli.
But both have their place :-)