From what I observed, most of the Realtors on Trulia are residential Realtors. You might want to talk to a few large commercial brokerage firms to find out more about the investment and rewards.
I do hear that the good thing about coommercial is that it's in some way, easier than residential real estate as they are mostly numbers driven rather than emotional, and once you make a great deal, you can enjoy that for years to come.
However, I will only be talking from what I hear, not what I know.
So, to find out more, go and talk to the source - that's the only way to find out if something as big as this works for you!
Although the other thing you must know is that if you work hard enough, have the passion, and believe enough, you can be successful in anything!