Are any of these sources telling you WHY to not use the HU?
I don't think it will reverse the rotation of the Earth or anything.....
Update:
Yesterday: I talked to Technical support at Crutchfield about the 2-Ohm/4-Ohm issue, and was advised not to use the Receiver with my factory speakers. He told me to call customer service, and see if they can suggest a Receiver that can handle 2 Ohm speakers.
Today: I called Crutchfield, and discussed my issue. I was assured that the Receiver I purchased would indeed work without issue with my factory Nissan 2 Ohm speakers even though there is an impedance mismatch????
Today: I called Pioneer Tech support and was advised to NOT use the Pioneer DEH-X6900BT Receiver with my factory 2 Ohm speakers. Also, if I do want to use the Receiver, I should replace all 2 Ohm speakers with 4 Ohm speakers.
Total confusion to say the least......