I used no-climb horse fence for the tops, only b/c I had enough leftover fencing laying around. Thicker than simple welded wire, but lighter and cheaper more readily available than hog panels. Posted via Mobile Device
I like the ideal of good solid walls of oak between stalls maybe leave 12" to 16"
At the top so air can move around. Across the front I like the half walls with bars on top. As for the doors have two peace doors that way you can leave top half open or closed as you please.
Can you post a few pics so we can get a visual of the stalls? By removing the bars you will be looking at considerable expense replacing them with something sturdy. Horse are great at finding weakness and will devote their energies to reeking havoc. That is why the iron bars were installed.
I prefer chain-link to hog panels. Had a VERY serious injury due to hog panels. The holes are large enough for horses (especially the youngsters) to get their feet/legs through and do serious damage to themselves trying to get out. Youngsters can also get their heads through the holes and hurt themselves.