Well look closely at my set up; I came up with a solution for that. Its my own invention and it works awesome.

I know the picture could be bigger but then I have to pay for the upgraded membership don't I. But let me just say this; I am using an extender on the brake lever that I have found on the internet and have modified it so that it is extended further out whereby I can now brake in all three positions that you are speaking of. I have been using this set up for about seven years now and have imporved it constantly to a point where I think it is perfect now. In fact some of my friends and family members liked it so much that I would say about 8 of them now have the same set up. I myself have three bikes set up this way: a road bike, a mountain bike and the Giant touring bike that you see here. And yeah you are right the three positions work exactly like you say it does; the first position allows you to sit up in a relax manner, the second position gives you the bar end grip, and the third position allows for an arero position if you set it up correctly; where the third position stis a little lower than the first position; where you can rest your arms on the first position while gripping the third position. To me this is the most versitle, comfortable, and just make sense set up you can have on a bike, where all three types of hand position is available while riding. Aero, bar ends, and upright sitting; what more is there.
And as you can see I like modifying my bikes to where it works the way I want too, like the Giant you see here, it is a touring road bike; but if you look closely you'll see that I have a suspension fork on it. It is a '29er fork where I am using 700c rims on it with 700x32c cross tires. Which means I can ride on fire roads very comfortably when decending. I also have a road triple on it; a 53-39-24 crank and a 12-34 cog. I can ride it like a road bike or like a mountain bike; very versitle I have to say. And one more thing on this bike I have disc brakes so when I grab the lever up front, it only needs a light touch to really slow my decending when needed. But this set up work's quite well on v-brakes also, and on road brakes too. So I don't see any problems with stopping with either v-brakes or road brakes which my other two bikes have and those whom I have set up with. It stops on a dime when I'm up front.