Come on man! Don't blame the refs. To be honest I still can't get over the call on Bowen at the end of Game 4, and to me, a phantom call is much more difficult to swallow than a non-call. It is also easy for Spurs fan to point to the imbalance in calls, when Dirk Nowitzki, a largely perimeter player, broke the record for free throws. Don't get me wrong, I do agree with you that there were bad calls both ways, and that the Mavs won the series based on aggressive play and better execution, not refs.
Elson and Butler are not improvements over Rasho and Nazr, I will have to concede, but I will take Marquis Daniels and Darrell Armstrong over ANY of your new additions. Deaven George and Austin Croshere got bloated contracts, Anthony Johnson is slower than a tortoise on a snail, Buckner is good defensively, but Daniels is better all around, I don't know anything about Maurice Ager.
The improvement of Harris, Howard could happen, but it's not a given. Howard has improved slightly over the last two seasons, Devin Harris improved statistically based on more minutes, and Diop has not improved at all in 5 years, I don't know where that came from. Dirk is already pretty damned good, so I am not sure what kind of improvements you are looking for.
I am not saying that the Mavs will not win it, but I will say that it is a stretch to dismiss the Spurs and saying that the Mavs can win in 5 games (that's saying they will win 4 out of 5 games, or 80% of the games in a playoff series). To put that in perspective, out of the 15 series last year, only 4 of them ended in 5 games or less. Do you actually feel that the 2007 Mavs is better than the 2007 Spurs by as much as:
Heat over the Nets
Pistons over the Bucks
Clippers over a chaotic Nuggets
Mavs over the Grizzles in last year's playoffs? Come to think of this, 3 of the 4 series were 1st round series, which indicates quite a large gap in talent.
To answer the original questions, it will be either the Spurs or the Mavs, with me choosing the Spurs of course, because the Spurs didn't play with a full bill of health last year, and still stretched the Mavs to 7 games, and contrary to your opinion, I actually thought the two teams stayed relatively unchanged over the post season.