Belt grinder...Vertical vs Horizontal

[SHARPCO]

   
Vertical.
Maybe most of you are using Kally vertically.

   
Horizontal
When I sharpen knives on the slack belt, I set it horizontally. I like it because I can see that removing of burr during edge is on the belt. 

But there is one inconvenient thing, replacing the belt is a little cumbersome.

And I think the vertical type is better when using Platen. Because I have to see the edge and belt contact.