I assume since none care about the msi card being OC'd, it isn't that big of a deal. I was sort of under the impression that the 5750 wasn't better than those cards and its only advantage was dx11 and whatever else HD 5000's get.
The MSI card being OCed isn't a big deal because it can easily be done on your own(almost definitely with better results.) So it doesn't really matter that it is done ahead of time.
Here is the relative performance of various cards at your resolution vs the HD5750, including the 2 you are looking at