Any motor on boost is as reliable as it's tune. Craptastic tune=craptastic motor/performance.
What do you plan to do with the car in the future? And how much more money, beyond the motor and upgrades, do you wanna spend? What chassis is the motor going to go into? Based on the fact that you are asking about a D15B, I would assume an EF or an EG.
Give us some more details, and we might be able to provide better information.