This is a get in the door tactic, then they sign anyway. i have taken expired listings after agents like this held clients to a 12 month period and would not let them out for any reason. Needless to say clients extremely jaded about our business at that point!
Build your own brand, find an out of the box reason and offer it to clients but stick with it. The problem with rebates is that after a while you feel as if you are being under paid and want to stop it. Many agents leave companies that do the buyer rebate because they realize they'll make more money elsewhere.
Every model has a place, just decide what you want yours to be and then stick to it.