We have been working on El Capitan for a while and we will release iATKOS EC if/when it is good to go. No time frame but so far it is fine.
As we test El Capitan, it feels good. It uses the processor wisely. Even if it looks like Yosemite (besides the beachball and the new Disk Utility toy :), it feels different. Graphical interface (GUI) runs flawless on multi-tasking, no trace during high CPU loads.
Current version is 10.11.1.