I'm guessing a COMBINATION of high rep and low rep work will probably yield the best results. I'm assuming the body will adapt and stagnate if you do the same rep scheme for months on end. You have to mix it up to keep the muscles "on their toes" so to speak, to allow it to grow. Just a supposition, I'm not making facts here. For me, I've been switching between 4-6 reps for 3 weeks, then 8-12 reps for the next 3 weeks, and then switching back and forth again. It seems to be working so far!