Worked like a charm - much better than the "enable handoff on an unsupported mac" script that's around too, thanks a lot. Incredible how reliable and current these 2011 machines are...No Night Shift on my iMac (21.5-inch, Mid 2011)
edit: enabled it using the patch mentioned here
https://pikeralpha.wordpress.com/2017/01/30/4398/#comment-9146
even easier: https://github.com/TMRJIJ/Night-Shift-on-Unsupported-Macs