i think you could fight a weakness in Rebounding through a weak rebounding PF/C with a very strong rebounder on the other position. Which is maybe not the best decision with the salarys, but i think it will work for the game.
With IS, in the past i had centers without IS who did their job when i played outside tactics, but i wouldn't play inside tactics with them even when the PF is a monster under the basket. So here i am for the balanced way.