Many municipalities have an ordiance stating whether or not signs can be placed in the right of way. Georgia for instance states that you can't place a sign in the right of way along a state highway. Is this always enforced, of course not. But I can promise you if it's my sign it will be.
I think the rule of thumb appears to be in Georgia, that it's up to the local "powers that be" to decide if a sign may stay or must go. I think we can all agree that directional signs are a great help to REALTORS in directing thme to a property. Especially if the property is located just off the beaten path.
So do you put them up and risk them being taken not with no hopes of recouping the money spent in the first place?