Proper line management is the key in my experience. (i am not a line manager)
The agent can determine if he wants reduced juice or not.
After line management you can start to add the other intangibles like software (very important), wagering, 100% english speaking clerks, differnt markets such as, horse and casino, and friendly customer service. Also, a good PPH manager to handle all the needs of its agents. All important qualities that will make a PPH offering stand out and provide important value you to your players.
Great questions BetLarge!