brakleybeach: I've had the $300 EMS (Progressive) for 5 years now. RVing cross country 5 times (snowbird) and quite a few "local" (5 hours or less) travels every year. Every time I setup...the EMS is used. ("Hanging from the post" as you say)
NEVER a theft problem. In fact, never heard of one. Any "theft" problem mentioned here on the forum is always "I know someone" or "I heard" or "a friend of mine"....never a first hand account.
just my opinion(s) and FWIW.