Dennis:
I see we have worked many times in contests, most recently in the CA QSO Party where we worked on CW on 5 bands and on phone, two more. I was using N1MM to key using RTS then, but I have since changed to something like you have where N1MM connects by Winkey mode, and the paddles go direct into the remote rig. The remote station is only about 5 miles away and we have Comcast on both ends, plus a 'double hop" Ubiquiti link to go from the property owner's home to the garage about a quarter mile away. You can see most of the equipment on my QRZ page.
I'm running the K3 through RCForb Server at the remote site and at the shack, RCForb Client and a K3/0 Mini. RemoteRig can work between the K3 and K3/0 Mini, but you lose the ability to run things like a SteppIR, band scope and CW Skimmer at the remote site and N1MM at home, so I only use it for CW keying and for the audio codec. I have enough bandwidth to run a real-time NaP3 band scope at the remote site that I view with Team Viewer.
It all works extremely well except once in a while when a few packets start to drop somewhere in the Comcast system. Round trip latency is usually about 27 ms, but with occasional jump to 100-130 ms. That's when 'dits' can turn into very long 'daaaaaahhhs', or get skipped altogether.
Ron, N6IE