Craigwagner6,
I recommend the double check valve assembly since your local building code requires it.
See Local Code Lingo Topic:
http://www.sprinklertalk.com/forum/topic.asp?TOPIC_ID=386
Both the PVB and DCA typically lose about 5 psi through the device. The DCA will lose a litle more than the PVB, but not enough to make your decision based on pressure loss through both devices.
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