I am not a fan of HMH either - though a big fan of IASWH and SMGG.
Not sure if anyone knows the answer but Sherry E on the Halloween Superthread might.
Up til last year HM went down on the day after Labor Day for 2 1/2 weeks. For those living abroad that would be the Tuesday after the first Monday in September.
However, last year Disney wanted to get a jump on the ever more popular HalloweenTime and they closed HM in late August to make sure it was ready for a mid-September opening as HMH. They also closed SM the day after Labor Day for five days (I believe in early September as well).
My guess is they will repeat 2010 and close HM before Labor Day to support a mid-September HalloweenTime launch. But it might already be decided and there is no need to guess.
See
Halloween at DLR Superthread-Part 2! SEPTEMBER 16 - OCTOBER 31, 2011!!!