How to attach PEX pipe to plaster walls in laundry room?
If it were me, I would go with #4 but use 1X6 instead, placing both pipes on the single horizontal piece. If it is plaster and not sheetrock, use screws to hold everything in place. You could even use it as a shelf ledger in places where appropriate. Use the black plastic device for all of the holding, except use longer screws where there is pipe insulation. The clamps hold the pipe without the screws drawn tight and the longer screws act as a standoff.