Maggie's Farm

I think your own Q&A sums it up:

Worth doing? I doubt it...

Maybe, maybe not.....here's a few articles for your consideration:

https://www.t-nation.com/training/bosu-ball-the-good-bad-and-ugly

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3325639/

http://www.menshealth.com/fitness/the-swiss-ball-youre-using-it-all-wrong

Hope you enjoy!

As for BOSU balls in my own training, I sometimes do a cycle of BOSU ball pushups (round side down) on the grounds that the shoulder is an inherently unstable joint (the shoulder is a ball and socket joint and the glenoid fossa is very shallow) and these exercises help develop stabilizers. I'm willing to sacrifice some strength gains for stability gains recognizing that I will at least maintain the strength because I am doing some exercise. Along the same lines, I also work in "down" cycles for vertical pressing (overhead presses) using upside down kettle bell presses instead of regular DB or barbell presses (I also sometimes simply substitute in rotator cuff work, i.e. lateral raises, etc.) - overhead work can take a toll on shoulders especially if you have "unfavorable" acromioclavicular anatomy. The older you get, the more susceptible you are to the ravages of overuse injuries, the loading phase of plyometrics (rapid eccentric phase work), new exercises for muscles that you havent' trained in a while, etc. and the longer it takes to heal from injuries.

BONUS ARTICLE:

http://tonygentilcore.com/2011/03/only-four-exercises/

Sometimes KISS is the best approach. As he mentions at the end of the article, I would probably add some type of pulling where the elbows bend - rows or chins.