advantage
1) The biggest advantage of playing a defined character is that you will have an instant connection with your crowds. They will know what to expect from you.
2) A defined character makes writing easier. Knowing your angle allows you to frame each premise towards your character’s sensibilities. Also, if you reach the stature of Larry the Cable Guy, it’s easy to hire a cable writer since they know his voice and the audience for him.
3) Your jokes become your jokes. They cannot be stolen or hacked. For example, if a comic tries to make “You know you’re a redneck” joke, or some variation of this, other comics will call it out.
4) The characters on stage become marketing machines. Fans gobble up everything from t-shirts and hats to DVDs and car decals, creating a surprisingly lucrative cottage industry for you.
5) Characters can be turned into sitcoms. Talent scouts who attend comedy festivals aren’t necessarily looking for the funniest comedian, but rather those with points of view that have potential for sitcoms. Ray Romano and Rosanne Barr are two excellent examples.
cons
The only downside is that you will always be typecast. Every time you go on stage you will be asked to be your character. There is no escape.
To understand this, imagine if you go to see Don Rickles and he never once attacks the crowd, but prefers to tell dog jokes. As a fan, you would be disappointed and leave the place feeling cheated.
Dustin Diamond, the actor who played Screech on the series Saved by the Bell, is a classic example. He now works as a struggling comedian. He draws crowds not as Dustin Diamond, but as Screech. Consequently, his fans are disappointed when they hear him tell jokes about marijuana.
Richard Lewis has been known to bomb when he deviates from his Jewish gimmick.
Once you’re established, you’ll be locked in for the entire trip.