I have a few in both configurations and the differences are small. The middy gas on a 14.5" barrelled rifle allows light recoil and faster followup shots than on a 16", but the difference is so small, it is not a hindrance. Some find the 14.5" barrelled rifle with middy gas is not quite as reliable with lower powered ammo (as in Tula), which is not a problem to me. I do like the handling on a 14.5" better, but again the difference is small.
The downside (to some) is the barrel device must be permed (without a stamp) on the 14.5", where it is easier to swap on a 16". This again, is no problem to me, as I prefer Vortex or AAC flash-hiders on mine and have no desire to swap them.
I followed the arfcom advice and got both. I tend to grab my 14.5s first, but if hunting, the 16" would offer just a bit more velocity (and range).
The differences in capabilities between 14.5/16" rifles is not great, either/both can do most equally (in my oppinion). YMMV