Bar loosing the display does changing the headunit affect reversing sensors in any other way or is it simply that you loose the display?

AFAIK if you use a third party HU that does not support OPS then it still works (i.e. it beeps at you) as it defaults to PDC only.

There are numerous members on here who would dearly like to get OPS to work - you seem to be going the other way

as soon as i get my octy (next weekend) and the right adaptors i'll be whipping out the headunit and changing it for my pioneer P77MP

You just lose the view of the car and sensor lines. The beeping sound still works on mine. I changed mine for a Chinese Head Unit.