Maybe another consideration in picking a broker is whether they have you sign an exclusivity contract with them for x number of months. Last time I checked, which about 2 years ago, Fidelity had that. Other brokers might not, meaning you might actually be able to list at more than one, although I'm not sure of the specific, or you could pull your listing from the first broker and relist it with another if you aren't satisfied with the first after a while.
I might be wrong, and if I am I'm sure those with more knowledge will jump in and correct me.