Well, I think there are lots of things to think about for a situation like this.
Most schools I am familiar with say that they weigh OAT's and GPA's equally. If this is the case, then the two sort of cancel out to make you an middle of the road applicant. In terms of "attractive combinations" obviously the higher on both parts the better, but there is really no way to predict what schools will want. I think in general they are not looking at raw numbers alone. How you come across in an interview will be very important.
A plus in your situation is that your GPA is high. GPA's are a good indicator of things that standardized tests can't account for (time management, ability to juggle many classes and other "life" stuff). However, all the schools require standardized tests because they are just that, standardized. It gives schools a way to compare an applicant pool of students coming from different colleges, different majors, etc. I guess what I am trying to say here is that OAT's are an important part of the application. If this is really bothering you, you could take the OAT again and prepare for the test-taking aspects of it.
You mentioned that some people are just not good at standardized tests. Although I know that is very true, part of doing well on standardized tests is simply knowing how to deal with the test being standardized. Whether this means focusing on material specific to the test, practicing with the same time restrictions, or practicing in a similar environment, you (test-takers in general) have to not only "know their stuff" but also be prepared for the whole experience.
Also, I have heard that OAT scores may correlate to national board exams that you will need to take later in your career, because they are similarly standardized. I can't attest to the reliability of this, but it does highlight that the standardized tests don't end here!
I don't know if that is the sort of reply you are looking for...I guess you asked for thoughts so here are some thoughts! I wish you the best of luck with the admissions process! Let us know how it turns out!