Alright, I'll go first.
1) I always worry about passing offenses that can make something out of nothing. Carolina and the Jets have made a living in the past out of big plays that occured long after NE stopped the original play call. I fully expect Dallas to have at least 2 20+ plays that happen due to Romo's athleticism.
To counter this, like a person said on Patsfans, I won't be surprised if NE plays more 4-3 style looks like they did in SB 39, to use containing pass rushes. I have no idea what Romo's passing numbers look like both in and out of the pocket, but anecdotally, he seems more dangerous making plays running around then he does as a pocket passer.
2) I just broke down both Dallas' and NE's passing stats based on 3 categories; ypa, comp % and passer rating. They look remarkably similar. Check it out:
Dallas
6.3 ypa
58.4%
64.8
PR
NE
6.3 ypa
58.8%
70.9
PR.
When you did deeper, however, things look quite a bit different. I also broke down the averages of the opponents that each team faced. (Caveat: I realize that I averaged averages and the dangers that this entails, but with five games each, I think that these issues should be minimal)
Dallas' Opponent Averages (+/- Dallas' numbers)
6.2 ypa (-.1)
59.3% (+.9)
69.6
PR (+4.8)
NE's Opponent Averages (+/- NE's numbers)
7 ypa (+.7)
62.5% (+3.7)
81.8
PR (+10.9)
NE has done significantly better against the pass than Dallas despite their overall nembers looking good. For all intents and purposes, Dallas has held teams to their average, which should be frightening to Dallas fans considering NE's averages (8.75/74.1%/128.7).
The sacks show simlar results. Dallas is tied at 11 with 12 sacks and NE is tied for 7th at 14. Again, though look at the opposition:
Dallas
Oppenents allowed 57 total sacks for an average 2.3/game. 12 total sacks equates 2.4/game.
NE
Oppenents allowed 49 total sacks for an average 2/game. 14 total sacks equates 2.8/game.
Again, it is clear that NE has performed better in spite of similar overall numbers.
3) I didn't run through a similar comparison with the offenses because, frankly, they are both excellent. I did look at run defenses because i thought that I would find similar results. Surprisingly both NE and Dallas have allowed 3.6 ypc against teams that rush for 4.