I think, in this case, I might be against shortening this tree. I'll explain why. I do love shohin. I am a big fan of a nice shohin. However, there is more to shohin than a fat trunk. A beautiful shohin generally has a powerful trunk, but nice movement. Although this tree would still be a very nice bonsai even if it was shortened. To me, you have somewhat taken away the movement and the essence of the tree. You are left with a thick, hour glass shape trunk, but no real movement. Just a trunk.
Here are 2 virts. I removed and added foliage where appropriate. Notice in virt one with a shorter tree. The eye is drawn to an almost hour glass like trunk that does not have movement. Also, right above that, the tree splits into a fork then there is an apex. To me, there might be too many displeasing things on the view on the way up. You have the hour glass, then a fork, then the apex. I believe this leaves the viewer wishing the tree was higher and that there was some movement.
Now notice in virt 2. With foliage pads in the appropraite places, the branch pulled down slighty also the swelling from the technique that was applied. You have a tree that has movement. As your eye goes up the trunk. You see a nice base, some dead wood, then the movement kicks in. Then, the top gracefully leans like an old, majestic tree.
Well, virts are easy. The true test is seeing the tree through to reality. Now, if for some reason, you do not like the taller version after a few years, you could probably chop it and start on the shorter version. However, once that top is gone, the plan of a taller tree would take many years to achieve.
These are just my opinions.
Rob