AusBonsai

If I had an army of hornbeams I wold most certainly attempt some of the suggested changes. As it is I have one and I'm really not prepared to take too many chances with it in search of perfection. I do However have a couple of much younger american hornbeams which I haven't started training yet so I can perform all sorts of shocking experiments on them.
Craig

As Sal would say... the tree is really too tall and you lose any power the trunk has in the extended length. My visions are
1) cut to the red
2) cut to the yellow - solid line first hoping it would shoot at the base of the top branch... once a shoot was established remove the branch at the dots.
Even putting your hand over the pic at either point you can see power starting to move to the lower trunk and you get a stronger more visually powerful tree. Yes, it will take time to redevelop the top but it is what I would do if I had the tree. I had a hornbeam in my first lot of potential bonsai and I found it very slow but I still think these options are worth considering. The deed to do or not to do is yours... just consider.