GMAT Score - how high?

my opinion is only an educated guess... i myself just applied (to harvard as well) and wait for their decision...

I think GMAT is considered twice in the process... i think there is a three stage process when considering an application:
1) initial screening (my guess is that at least 50% of applications are rejected at this stage)
2) finding suitable candidates (choosing about 50 final candidates, each is a suitable candidate for phd, and if there were enough faculty and budget to accept them all, each could have been accepted without reservation)
3) choosing who to accept (about 30)

in the first stage, GMAT is an important factor. it is considered as a "threshold". 710 and 750 are same here. if you passed the threshold on some parameters you are on to the next stage.

in stage 2. no consideration of gmat is given. it is your SOP, LOR, research and employment history, research interests, detailed account of your undergraduate (and graduate) studies...

stage three is where, in my view, GMAT can help you again. this stage is all about "standing out". there are about 50 good candidates and only 30 will be accepted. it can be a very high GMAT or a LOR from someone faculty knows or an initial correspondence between faculty and candidate or whatever makes one candidate seem to be "better" over another. here 750 can be more valuable than 710. i.e. everything else being equal - they will probably accept someone with GMAT 750 rather than someone with 710.


again, this is only my assumptions and model of the admission process. so it is just an educated guess.
as tkkoh commented - do your best on GMAT, it is something that is up to you.

good luck

amit.