For those who haven’t updated to El Cap yet or don’t follow the Twitter feed, yes, Hazel runs great on El Capitan (OS X 10.11). There are no known significant issues or bugs at this point and the current version runs fine as is. The only problem that I’ve found so far is an obscure and extremely minor UI feature. I will be issuing a patch at some point but there is no hurry on that front as I’d rather wait for some real El Cap bugs to surface.
If you do find problems, please report them to me. You can (in decreasing order of effectiveness) email support, post in the forums, or tweet. Those are the places I check and can confirm and fix the bugs I see there. I won’t see posts on other sites so please consider posting to one of the above places first. Whatever you do, please do not give credence to random statements about compatibility on other sites, especially when those statements were made months ago on an early beta of El Cap, and even more especially on a site with “rumors” in the name. I’ve received enough emails referencing such posts that I feel the need to weed those out specifically. Remember, this is the internet so choose your sources carefully.
In the meantime, work is continuing on version 4. I can’t say when it will happen but I will be doing a beta at some point so keep an eye on the aforementioned official channels for updates.