I routinely run two 7.2V packs wired in series (14.4V) to one of these motors in an 11 lb. 36" long boat. But I have added water cooling to the motor. In any case, it handles that voltage easily. You should not have any problems running 14V to these motors. Your run time will depend heavily on the mAh rating of the batteries. It sounds like money is not an issue for you, so you should think about getting the new 4500 or larger mAh battery packs.

I have read that when running two esc's that each have BEC capability, it is very important to disable the BEC on one of the esc's. You should get more info on that by doing a search or asking a new question about that in the forum.