I found it was hard to get a good deal on a used regulator, seems like everybody knows their value. I wound up buying that model except new. Agreed, if it woks, its a good deal. That's a very popular model so you'll find others in the community with helpful tips.
Make sure to follow the very vague instructions for setting it up. I've seen some in the community say that the needle valve is easier to adjust and keep adjusted when the operating (low) pressure is at 20-30 psi, which contradicts slightly with Milwaukee's instructions.
I forget the setup instructions (which I'll have to look up again when I get the tank replaced/filled), but I remember one important step was to open the main valve of the tank very slowly so as not to blast the internal workings of the regulator. Make sure to look up instructions for it; as said, it is a popular model and the interwebs have lots of good info on setup and running it.