We have been occupied with Sierra lately.
There are many issues with it as it is pretty new. USB problems (like 10.11.x), Core2Duo/Quad CPU computer incompatibilities, Broadcom WiFi support etc.. Some of these issues make it impossible to install retail. We are preparing iATKOS SR which includes the solutions for most.
No time frame, no ETA but we are close.
Last few days' requests will be processed very soon, sorry for inconvenience.