My note 3 is working great, except the GPS. From what I've read, the newer radio versions do a better job, and I've compared my phone's gps performance to newer ones in the stores, and it seems to be true.
My phone is still under Samsung warranty, but I don't want to send it in, and possibly receive a refurb with more problems.
I've opened up a friend's note 3 to replace the front camera and sensors, and it was straight forward and easy to do.
But I can't find a gps radio replacement anywhere.