>"Is there an engineer in the house?"
My degree is in aviation engineering & I used to be a sound engr, (20 years.) Capo-ing will not increase stress, except as much as constant bar chording will, i.e. minimal.
That's why it works, you get easier action tuning down and then come back to 440 by capoing, nest pas?
p.s. I recognized the pictured capo marks, can't remember the brand but I still have one of those awful damn things but never use it. It's a keepsake;-)
Question: Is Kyser the 'lemon squeezer' type? I have one of those too, it seems like a lot of hardware gets in the way.
p.p.s. 'guitar elbow' might be alleviated by letting your arm's weight help make the chord instead of relying on strength. Kinda a 'classical method'. As always, INAD and YMMV, and others in this forum are better players & more knowledgeable. Maybe they can set us both straight.
Quick aside: I remember Van Halen's live sound engr telling me that David Lee Roth's voice would gradually lose it's range during live tours (gee, I wonder why?) and the whole band would tune down together so he could still hit the high notes. By the end of the tour Eddies strings were so lose you could hear the fret slap. Dog nose what Michael Anthony's bass sounded like!