Bump with update:
I sent the Phase One P20+ back in for a check up because it developed noise beyond a normal operating back, and Phase One Denmark did the following: Recalibration, IR-Filter Exhchanged, Repair of Flash Card Circuit, Firmware Update, Repair of Power Supply, Image Capture and Inspection, Focus Inspection, Cleaning, and Visual Inspection.
I had no idea that there was any issue with the IR-Filter, focusing, etc. because the back was operating fine, but Phase One was able to scrutinize deeper than what was obvious to me, and I am grateful that their comprehensive warranty service brought this back up to their standards despite the fact that I had no idea of the issues they fixed (I only noticed the noise issue). The warranty is still in effect until June 2011 and I will help the buyer in any way possible if there is an issue, but that is unlikely because of the recent (March 14 2011) service by Phase One.
To those of you who previously expressed interest, please understand that my reluctance to sell was because I wanted to follow up on the noise issue and in hindsight it is for the best, the back is now available in the condition it should be to sell.