"We're in Michigan so no repiping thru the attic." For my education-is this a cold weather problem or plumbing code problem? I have seen homes in this area, deep south, built in the early '70's with copper piping run in the slabs without insulation/protection develop leaks. For a few years plumbers ran new galvanized pipe service into these homes right up the outside of the front of the house, insulated it with black foam crap that lasted about two years or so, the plumbed the rest of the home from the new service line. Then came PEX. Plumbers started bringing the PEX up about a foot and then through the wall of the home, who knows which room was on the other side, and continued from there throughout the attic and into where it was needed. Whether we like PEX or not, this was a better, "cost efficient" solution. I believe I understand your concerns about future potential problems. But would PEX, or some type of flexible tubing/piping be a "cost effective" solution? Good Luck, David