I went ahead and rooted using the Kingo method. The method is considered controversial. I am not equipped to discuss the technicalities of it, just reporting my history.
I seriously missed the abilities provided by a custom recovery but I did not want to trip Knox. Wanted my cake and to be able to eat it too.
Predictably, I got my phone into a state that i was not happy with and ended up installing a recovery using Odin.
I have to admit that Odin initially put me off and it took a bit for me to figure out how to use it. Now that I have used it, I am pleased as punch. It works fine, lasts a long time!
Subsequently, I have been on 2 of Freeza's Roms, the stock rooted and his debloated custom. They have both worked great for me, though I did have to use his wifi patch to get my phone to remember how to connect to my home wifi.
If I had it to do over, I would root using Chainfire's method above, with Odin. I would immediately install the TWRP Recovery, [RECOVERY] TWRP220.127.116.11 TeamWin Recovery Project 10/23 - xda-developers
and make a nandroid backup.
Rooting was a step I was reluctant to take with this phone, for some reason, but now that I have, I am glad I did.