If they held shells that tightly it would impair you from removing them quickly.depends.
On the side saddle I had on the strong side of my stock, I carried brass down. reach under with my weak side, pull down and its lines up to slide in the magazine.
I haven't run a side saddle on the weak side of my receiver, but I would say it would be the same. Just keep your weak side hand out from in front of your face.
As far as recoil causing the saddle to drop shells, its time to consider a different brand. a quality saddle should hold the shells without issue.