Anyone ever use freeze protection valves?

[gsganzer]

I was at the new place today and started looking at freeze protection, with some cold weather in the forecast.

Has anyone used freeze protection valves? The house has 4 outdoor sillcocks (all the freeze proof variety) and I just put the standard foam covers on them. But there're two other spots that give me concern:

1. There's a hot/cold freeze proof sillcock (I didn't even know they made a hot/cold option), mounted near the hot tub, on a stand-alone patio wall (unheated wall). I don't know how that line wouldn't be at risk of freezing. It's routed on the backside of a wall that has the outdoor fireplace, with no connection to heated space. I'm thinking I should put one of these on both the hot and cold. Freeze Mizer Valve
2. In the shop, they have some lines that come up from the slab and then run about 12' to a bathroom. I can put a milkhouse heater in the bathroom, but the other parts of this line run through the unheated shop. I'm thinking of cutting in a tee on the lines and put this style of freeze protection valve on them. The discharge could be routed outdoors or into a bucket.Freeze Protection Valve

Anyone have any experience with freeze protection valves?