There are many pro and con to have your own agent.
Pro.
1. You can always negotiate the lease on your terms. You can ask much more when you are not actually talking to your landloard.
2. Most of the time your agent will work on your behalf. Without them, you will need to do all your due diligent on your own. (Not all the agent will do this)
3. Your agent can also compare price around for you. What is available and how much it cost.
4. If he/she is experienced agent, they can tell you the property history or type of business is coming or going in the area. This will ultimately help you project your profitability.
Con.
1. Their commission is 1 month per 12 months lease. (normally) They will always try to have you sign 5 year lease plus 5 years option or longer to maximize their commission.
2. You can do most of their work if you have more time on your hand. It is not rocket science.
3. They can also hurt you by giving false security.
There are many more cons and pros to have your own agent when you are looking for commercial space but if you know of very experienced, honest and hard working agent, it will be your advantage to have one.
I personally always use agent to find, negotiate, and purchase my commercial building.
Good Luck