Does anyone have any expirience with CCHP?  How about the ACADIA model from Hallowell?  As per my findings in the postings at the internet they do really work. Any comments? 

This is the first I'm hearing about them, it looks impressive, but I assume it still has to go into defrost mode on occasion, robbing it of some of it's effieciency. It looks like a great upgrade to anyone's Air Source heat pump system, but I'm not sure how pratical it is for a retrofit, since the duct work required is even bigger than Water source geothermal ducts.

there is a long debate about it here. i would be worried about maintainance costs eating up any savings.
http://ths.gardenweb.com/forums/load/hvac/msg1115313614618.html?89

Take a look at the Daikin system, particularly their VRV, for variable refrigerant volume, heat pump. It has a COP around 3 at 10°F. Web site is Daikinac.com. That's what I'm going to be installing in my currently under construction ICF house.

The biggest difference between Daikin and Hallowell is the Daiking system is continuously variable in it's output whereas the Hallowell is a staged compressor unit with 4 distinct operating levels. The Daikin is also a split system where one outdoor unit can handle up to eight indoor units. I believe Hallowell is one outside and one inside, just like most all residential ac systems.

If you're really into the techie side of things you can download the engineering data and installation instructions for the Daikin units from their website.