This is more the issue my friends have mentioned:
"Since the eccentric has only a limited range of adjustability, in some cases, it may not be possible to use even-size synch chains: if you replace a pair of 39 tooth rings with a pair of 40s, you need to adjust the eccentric 1/4" closer to the fixed bottom bracket, or you can add a link to the synch chain and move the eccentric 3/4" farther. Some eccentrics may not permit this amount of adjustment."
And I don't think you BLATHER.
You know more on the subject of Tandems than I ever want to and I appreciate your sharing with us.