A prime example is Killzone 2, if you havnt played it ill explain. People constantly abused of the class system since the engineer class was clearly overpowerd by its sentry bots and the fact it only had a shotgun.
Also since engineers can boost their weapons it would just like Stopping power and magnum ammo from COD/BC2 giving an unfair advantage to engineers.
Although this is probably not going to happen, I just dont want the engineer to be abused like in KZ2.