We all know KG is better than Marion.
But to assume KG will fit in as well as Marion is just what it is.. an assumption.
It would be better if you trade Amare for KG, but everyone here doesnt want that. Marion is a different type of player, KG cannot roam around like Marion.. KG cannot cover the perimeter all game. His effectiveness will be neutralize if you send him guarding the perimeter... KG needs to be where Amare is during defense... and during offense.
Having both and assuming each can score 50 points when guarded single handedly is another myth. The Suns revolve around Nash and finishers. Amare is the go to guy when the game slows down. Having KG there with him and assuming they will score every time they get the ball.... what exactly will they do differently... they will most likely run into each other... and if not KG will be on top of the key taking jump shots or finding Amare for the finish.... the Suns have that now in Diaw, Thomas, sometimes Amare and league MVP Nash. My point being, the Suns will go a lot of changes with KG there to be effective, you lose the wing man in Marion during fast breaks, you also risk losing Barbosa, as the wolves will not part with KG without that type of player... so you lose Marion and Barbosa... who provide so much for this system.
But in no way I said Marion > KG....
just that Marion has been working well with the system, he and Nash has been the common denominator in the Suns successful system.