I think it's close. Avengers opens almost literally with nothing out(it's been a very weak april and even march for that matter) with only THG and it's fast diminishing numbers. So it only faces a hungry audience and I'm not sure what the buzz is for DS but battleship so far looks to be an under performer. If Avengers doesn't hold top spot against these two that would be bad news for marvel I think. Then 3 whole weeks later it's "MiB" looking to be in strong form, but it's also memorial weekend. I compared this May to the May of 2007 earlier...
Batman not only has to deal with a much more stacked summer than it did in 2008, it will be coming in two weeks after spidey(very different from what Avengers is coming in facing, this bo dude things it's going for 300mill?) and a week after the always consistent Ice age. TDKR or rather Batman may have young fans in spite of Nolan's wishes but unlike Avengers(which seems more kid friendly) it has to deal with this kids being drawn to Ice Age just a week prior, again very different from Avengers.
Moreover unlike in 2008, TDKR has post release competition(in a similar genre to boot) to deal with. Now I'm not saying that either (Mat Damonless)Bourne or (Arnoldless)Recall will be a show stopper, but together on the same day(just two weeks after bats, is equivalent to combining both of their figures together. For example, what if both Dark Shadows and "Mib" opened up two weeks after avengers? It would be a combined figure enough to knock if off the top.
Lastly the late summer release is a blessing and a curse, sure there is less competion, but supposedly people actually take vacations during that time, it might not have affect TDK but then again maybe it did.
In conclusion, I do not agree that TDKR has faces less competition than Avengers this year, it's just different.