I think we'd be fools not to want him back for free; however, I think Danny's been proven largely right. Perk is a good role player, but nothing more. He's a liability to have on the court for more than 25 minutes per night, provides essentially zero offense, and isn't that great of a rebounder or shot blocker considering the other limitations of his game.
Still, of course I'd love him back to play 20 mpg off the bench. He's still an elite team defender, sets tough screens, and provides a physical presence.