Thanks for the feedback Joe. Things are a little slow on this forum... maybe most people are just busy trying to stay warm !
I think I'll be using a Belimo zone valve which is motor operated "slow close", not solenoid. So I think I'm okay on the water hammer issue. It is rated for up to 75 psi shutoff, normally closed, and spring return, so it should shut if there is a loss of power to the unit. Best part is I got them for way cheaper than the TACO valve.