I really think getting him in is a no brainer IF Rooney was expendable. Having both him and Rooney as guaranteed starters leaves little room for Rashford, who I'd rather be getting games for us.
Rooney's the right age for us in terms of blooding in a young striker, to be honest. Because we play with only one up top, a 31 year old striker as the main goalscorer with a couple of young strikers as squad players is the ideal situation. Of course, it would help if that 31 year old striker was actually of some quality, eh?