For me the pros would be access to MLS as well as hands on experience I get from the agent/Broker's perspective. I'm able to understand and further my knowledge of real estate investing especially when I do deals for investors. Not to mention i could argue that investors who are agents and brokers have better access to deals, show properties for themselves, submit their own offers, save on closing costs ( which really adds up when your investing really takes off ), and market yourself to other investors and provide a second source of income when you help them find deals.
The cons for me are the monthly fees. Mine are only about $100 per month. I know other people who pay almost $300 per month! Some might argue disclosure is a con, and I can see why but it doesn't bother me. However I do feel that being an agent makes me more susceptible to law suits due to certain agency laws and conflicts of interest.
All in all I still support the idea that having my license does more good than harm.