Just a quick update, I have both the PVR and non-PVR on coxial again and experience the shuttering and poor playback with recorded content even when using the fast foward instead of skip.
Here is a quick summary of my test results:
Best - PVR (CAT5), non-PVR (CAT5) - no issues
Acceptable - PVR (CAT5), non-PVR (coxial) - cannot skip, however fast forward works
Not recommended - PVR (coxial), non-PVR (coxial) - even fast forward will cause issues, however pure playback works okay.