I did. I don't need precise control of the colour, and I don't need anything too extreme as well. But I prefer to go for 9.3 for a more smooth iOS experience (my 6+ is not smooth on 9.0.2, but much better on 9.3 regardless if it's JB or not).
TBH, my 5s is perfectly OK with 9.0.2, so I know it's the OS not well optimised for 6+. I keep my iPad and 5s jail broken, but upgrade my 6+ to 9.3.1 now for better experence.
IMO, night shift is OK only if you don't need precise setting. The range of colour temperature also much less than f.lux offered. If you really prefer a very warm colour at night time, night shift can't do that.
Also, if you turn on the power saving function, you will lost night shift. If you need both functions work together, you better stay jail broken.
But the schedule function on night shift works well. This is on par with f.lux. Also, the native control in control centre also works quite well (especially if you have the 6s).