IMO the Suns have more talent than the Mavs yet they still missed the playoffs. I think Shaq would be a major upgrade over Damp but I don't know how far that gets the Mavs. IMO the Mavs are built to win against traditional teams like the Spurs, Jazz, and Rockets, this move would probably help the Mavs in that regard but high scoring teams like the Nuggets and Lakers would still destroy them.
I'd be very interested to see how that move to the Mavs would work out because the Suns experiment has obviously failed for various reasons.
I think that this is the perfect fit for the Mavs, and that this would strengthen the Maverick's biggest weakness - no inside offensive game. They'll be a high-scoring team, so the Lakers and Nuggets certainly can't overlook them; you can play the same game that Orlando is playing, except that your power forward is a 7-footer who averages double digit rebounds. The Dallas backcourt is strong if Kidd returns, and Howard is talented, although somewhat flaky.
And the Suns do have more talent, but it's not talent built to give Shaq operating room. Grant Hill is still a slasher rather than a shooter, and Stoudemire needs time in the low post to be effective. Barbosa is an accellerator, which isn't a Shaq-game characteristic, and Richardson is deficient as a post-entry passer.
I think Shaq makes a better fit in Dallas than in Phoenix.