Well, the Bulls still run most of their offense through Rose, and LeBron can still shut down Rose. Deng is still hurt (wrist) and not shooting well enough to offset LeBron's offense. So I think it'd play out pretty similarly to last year, really. I may be wrong, but I think the pre-All Star Break Heat is much closer to their true ability than this post-All Star Break version - I think they've been coasting for a while, waiting for the playoffs (since they know that's the only way to redeem themselves, and no-one gives a shit how well they do in the regular season anymore). Pre-All Star, their D was ridiculous, and perfect for trapping a perimeter player and capitalizing on turnovers.
Ultimately, I think team D will cancel out. The Heat have been outscoring their opponents by 7pts or so, the Bulls by 8. Neither are great offensively. The difference is that in a playoff series, the Heat can have their 3 big players play more minutes, and have the scrubs play less. So they project to be more efficient on both ends. And they have the ability to unleash LeBron on Rose at any time (I don't have Rose's stats from last year when LeBron was guarding him, but basically LeBron made him look like a high school player. Rose is better now but not that much better). The Bulls can protect the rim, which is huge against the Heat, but they can't stop all 3 of 'em.
So, unless there is yet another bizarre mental fade (which is impossible for anyone to predict, no matter how hot you think you are at armchair psychology), I'd say 4-2, Heat win, but with noses seriously bloodied.