Well fellow Jaycolites - the hits KEEP rolling in!
I solved my hot water heater issue (thread in the maintenance / repair forum) - good old user error.
I believe I found the source of my 'noise' when running the water. I noticed last night that the hot / cold was correct at the kitchen sink, but reversed at the bathroom.
Then I realized all the PEX lines were removed during floor repair.
Sure enough, they had the hot water return plugged right into the cold water line near the low point drains. My theory is that water is coming in from two directions causing the flows to fight each other - hot return coming into the cold line right at the city water hookup.
I have line disconnected lose now, should have them flipped in a few and another test performed.