I would only recommend retaking the test if you're sure that you can improve your score up to 650+. You still do have a shot at the schools you are targeting, and if you are working on applications, it may be better to spend your time on those apps. If you know you can do better, and have done better on practice tests, it may be worth a retake.
Timing issues are huge on the GMAT, and something that can really be a drag on your score. With an 80% Quant, this will look very good, but the verbal will make it seem that you are not good with English, or that you didn't write your essays. Sooo... Only you will know if you have the ability to improve.
It sounds to me like you really do have the ability to improve! That timing issue was a killer, and you should never spend too much time on 1 or 2 problems... espcially b/c you probably won't get far just looking at two answers. It will be 50/50 no matter how long you look at it. Guess, and move on. So, if you do take again, you HAVE to improve. I would recommend taking practice tests, and really working on timing. Also, know your checkpoints. You have to be at a certain point on a certain problem in each section, so you don't fall behind. If you're behind, find a hard problem or two, and make an educated guess.
Take a look at my post here:
10-tips-to-improve-your-score-app-with-no-extra-studying-124393-20.html if you are considering a retake. This may help you with your nerves. Good luck, and let us know what you decide.