Oxygen systems

I am considering the Aerox DDO2 mechanical diluter demand system. I
only occasionally use supplemental O2, mainly for the a few trips
each season to fly on the east side of the Cascade mountains in
Washington state. I am currently using a Aerox regulator with a
needle valve, and an Oxymiser cannula. Since there are no filling
facilities where I fly I am hoping to get a little more mileage out of
my tank. Could somebody out there provide some feedback on the DDO2
regulator? Is it a good option for the occasional O2 user? Does it
provide a significant reduction in the amount of oxygen required? Is
it easy to use? I don't care for the " string around the neck"
option. Has anybody mounted it to the interior of their cockpit? Any
other information would be appreciated.

Ron Clark