OPA227 datasheet states your R3 should always be used (so the trace cut on your PCB) when in unity gain follower mode if the source is able to drive 20mA or more into its load.
Assumed page 6 Absolute Maximum Ratings |Vin|<|Vs-0.7|, for a +/-15V supply R3 would be 14.3/0.02=715Ω to be sure any allowed input voltage won't break noise and drift specifications (see bottom of page 17). IIUC, as long as we don't use your R2, gain remains 1.
So whatever the gain we set, 1 or higher, we always should use R3. When in gain>1, I don't know if R3 still has to play this input protection role, and if yes, how do we calculate it.
Thank you for your job. I forked it to add the RF extra protections and a THAT1206 receiver here: http://www.diyaudio.com/forums/analog-line-level/220892-1646-balanced-line-driver-pcb-3.html#post3268215