Before anything else, Noel makes zero sense since he'd be only a rental. He doesn't fit the young guy with potential to grow in our system label since if we traded for him his bird rights would not come with him, and we could only then sign him with cap space next summer, and we won't have any.
Also, in this scenario how are we taking on two players? We only have one spot open and the DPE doesn't give us an extra spot, just cap space. Without trading/waiving a player we can only take on one.
That said I'm all for maximizing the DPE's potential to net us a long term asset. Grabbing a guy in a funky contract situation (for instance Okafor, but only if he's waived by Philly) makes a ton of sense to me. Okafor also gets us a player with a tool/skillset that we don't currently have. There have also been scenarios presented where we use the DPE in tandem with a trade creating a future TPE, and that would be awesome for flexibility too, but the guys who make sense to use in that trade have all been playing great.
I like the ideas of the players you mention, but these are all bigger moves than I'm expecting/hoping for. If a player Ainge has always liked somehow becomes available then pull the trigger with the DPE, otherwise hold tight and maximize its value for us long term somehow.