My knees and western saddles have never really gotten along well - but I found a mostly cordura western saddle that really appears to fit my horse - no rubbing, no soreness in the loins, and the saddle did not slide to front or back going up and down hills. (It is made by Dave Genadek at aboutthehorse.com.) Sorin was even able to reach around and scratch a spot behind the girth when I obligingly lifted my leg out of the way. He couldn't do that in the sportsaddle!
The problem of course are my knees. (And ankles.) Has anyone ever tried those special attachments to hook the stirrups to that pivot, taking the strain off of the leg joints? Please let me know what you think of them.