If your property is listed on the MLS you are already getting the best exposure available.
Even if another agent says they will market the unit to a broader audience, it won’t sell any faster. Price is the main motivating factor. If listed on the MLS every agent is aware of the property as well as all other properties that are listed. A property will sell if priced appropriately for the market. All agents representing buyers have a fiduciary responsibility to make them aware of all properties available within their range.

No one buys in a vacuume. All buyers want to know all propeties that are available within their range and the only source with this complete information is the MLS.