JBJ:
I think it really depends on the other characteristics of your application, and whether your score is balanced (9-9-9) or uneven. If you have a 7 or below in one section, I think that to send your app in early won't do a whole lot to get you acknowledged earlier. If schools think they might interview you, they will probably opt to do it later once they have reviewed more appliacations and see where you fall within the pool of applications.
Also, it depends on where you wish to go to school. The difference between a 27 and 30 is a big deal.
The MCAT sucks, but think of it like this...
Would you rather apply earlier w/ 27 and potentially not get in or give yourself another shot to make your application the best it possibly can be by taking Aug MCATs and doing better?
I was in a similar circumstance last summer (and I had applied once before) and I chose to do August MCAT (actually spoke to people who sit on med school adcoms). Fortunately I did well on MCATs, but realize that there is something you can do to strengthen your application a WHOLE lot. Taking august MCAT, and scoring better, could end up saving you a whole lot of time, energy, and money in the long run.
Keep a long term vision. This is what will get you through the short term frustrations.
good luck