If you can get Koufos cheaper its a no brainer. He can catch, finish better than Asik, is much more mobile, younger, and a good rim protector.I am fine moving forward with the sf combo of QPon and DC. If we can get DC back on a good price, we are fine at the sf spot. Not every team is going to have Lebron, Melo, Durant, or Leonard. For what we need from our 3 spot (good defense, 4th option on offense), those two have been plenty fine. If you want to make an upgrade then go for it, but its going to cost a lot more, and the improvement won't outweigh the price.
If Asik wants more than $9 mil you can trim the fat there. What he will command, and what he deserves are two different things, he can rebound, but he is a liability on the other end of the court. If you can save money by signing a Koufas, do you do it? I think the savings, and the lack of head scratchers on the offensive end would be worth it. What you lose on the boards (you gain in points and fewer to's).
I know we will be better wether we make moves or not, but everyone else will be better as well. The Thunder will be healthy, The Suns will be healthy, the Jazz will be better. Luckly the Spurs and Mavs have to get old, but for all the talk of us certainly making the playoffs next season, its no certainty given that the NBA doesn't operate in a vacuum where we are the only team improving.