One caveat is that since you're Detroit based, you're in a fortress hub where upgrades are going to be very few and far between for you on Delta. As an AS elite, you'd be at the bottom of the list below even silver medallions when flying DL.
If mileage accrual and redemption is more important to you, though, AS is totally the way to go... just realize that upgrades will be scarce on many major Detroit routes if that's what's important to you.