Has anyone had experience with a natural gas heat pump? Engine driven, not absorption type like the large commercial units used to be: http://ecovaire.com/press.asp The systems look very good, and just like the mini-split systems that were available decades before outside the US and are now finally starting to take off here, this looks like another vastly superior technology that is is only just now starting to trickle into the US I currently have an AC/Natural Gas split system on my basement/1st floor, and an electric heat pump for the second floor. The heat pump up stairs is flaking out on me, and if I have to replace it I really like the idea of putting in something allot more efficient. The natural gas units are also multi-zone so I could also replace my downstairs unit and dramatically lower my electric bill in the summer too. The main problem with stuff like this since it's new, it's hard finding installers that are familiar with tech like this or that are even willing to talk to you...