To get the answer you're looking for, you'll really need to provide more information on what your friend typically shoots, what lenses they have now, what the total budget is. If you only have ef-s lenses then you'll need to invest in new glass. If you already have ef mount glass, it will be an easier (cheaper) transition.
Your original quesiton is too vague--it's like asking, "My friend currently has a 2009 Toyota Camry, but wants to buy a Land Rover and has the money, should he do it?" Yes if he wants to climb mountains. No if he wants to race it in Monaco. Yes if he simply wants a top end luxury SUV no matter how he plans to use it. It depends on what he wants to do with it.