Well, actually we do have something to go by: the "school" tests in nuTrek. We have a way of comparison, just take a look at how today's IQ test are set up. If humans and Vulcans were to take them the result would be Augment IQ > Vulcan IQ > Human IQ. Given that humans always - as far as we know - over took the Vulcans in the development department, we could say that the humans are perhaps more creative then Vulcans. Vulcan can remember more - which should be an positive (in the future you need a greater mix of knowledge to come to new idea - at least according to a theory I read somewhere), but it is not seen anywhere. Perhaps the answer is this (I will use IQ as an example) Vulcans are 120+/-5 to human 100+/-40. So humans have a higher chance of a genius, or an idiot at the other hand, then Vulcans. And if you calculate in the population, humans have an advantage.