I just replaced a sillcock that froze. Thought they weren't supposed to do that, but it did.
Easy replacement and worth the effort. Go with a 1/4 turn unit. My old one was multi-turn. New unit is much much better. If you can't find the exact length of your old sillcock, go with one as long as possible, given your plumbing constraints wherever your pipes are in the house. The longer the sillcock, the more is "inside" the house, and less chance of freezing.
My recommendation is don't bother with the vaccum thingie, just replace the whole thing. $20 well spent.