Does the water being shut off actually cause a
water hammer, ie the pipes banging around?
Or is this just a theoretical concern?
If it's the latter, I wouldn't worry about it. *I've
heard a lot of people complain about water
hammer from a noise point, but can't recall
pipe failure being attributed to it. *I guess it
could occur, if it's bad enough.

There may not be water hammer, since I already have a pressure
reducing valve installed where the water comes into the house, but I
can sometimes see the hoses jiggle a bit when the washer shuts off
with the valve open all the way.