I would suggest you explain what part of his control he struggles with today. Does he have lots of hypos? Does it struggle at certain times of the day? Does he get hypos when exercising? Or do diabetes put him off exercise?
The reason I ask all these questions is why the pump provides better control: it allows you/him to adjust the basal at different times of the day rather than the basal injection which assumes his needs are the same 24 hours a day.
Bear in mind, the pump is not easy and requires investment from you and your son in terms of much more accurate carb counting.
I have been on the pump for just over a year and, as I exercise a lot it has helped massively.