Sunnyside, I changed over to the vertical exhaust on my 3520/cab tractor for a couple of reasons. I didn't like the exhaust in my face with the horizontal exhaust when I was getting anything out of the bucket by hand. Another reason was when mowing or working on dry dirt or a dry stone road in dry conditions the horizontal would stir up a lot of dust and debris. Not a problem for my lungs with the cab tractor,but that extra dust is being sucked into the tractor's air cleaner and cab filter.
The horizontal also made the tall grass move next to where it exited and gave me the illusion when caught out of my peripheral vision that something was being hit with the front tire causing it to move. Something was moving where it wasn't supposed to be moving. I didn't like that feeling.
All in all I'm satisfied with changing over to the vertical exhaust. The cons to it are cost, having to remove it to lift the hood and I just had mine get stuck on because of some rust. The install takes less than half an hour.
Sincerely, Dirt