Bottom line, Greybeard: The 9865HDC with Trio (Contour) interferes with CEC. There are several after-market solutions to the problem. You say you already knew of these, yet "The box interferes with it [CEC], such that I (and others) have had to turn it off in our other devices." So, you would rather disable CEC in your entire system than spend ten bucks to end the 9865HDC's interference with it. Looks like either A) you really don't desire CEC, or B) you really weren't aware of the after-market devices. One other "solution" for you is to use a different DVR. The 9800 series paperwork does not list CEC as being software controllable.
Simple enough?
BTW, you must look odd with HDMI cables "coming out of your ears."