Ah... Phooey. All humans may be created equal. They are not the same. Ive used 10s for 40+ years. If I could have only one, it'd prolly be a 10. The couple serious birders who lead Golden Gate (aka Audubon) Bird Sanctuary groups, Ive met use 10. And none have visited Birdforum that I know of.
IS is no doubt a thing. Its coming. Soon these will look more like the binos we think cool to have and hold. Soon they will put the good glass in them. Soon we will want them. Now? A work in progress.
For many most, using more mag is a learnable, trainable thing. We go to the gym to get strong at some activity... right? If you shake too much with a 10 now, why walk away from the benefit - it is there - just train bit. Maybe just go out and use them for awhile. we adapt. By the way, while the convo re wrists, hands, arms is interesting. Pronate and supinate? Had to look it up, thought that was foot thing, shaking starts at the ankles.
I own 3x8, 2x10. Thinking about a 12. Have no idea why a 7 or 6. My worst shaker? 8x25. Why? Its light. Hmm mebbe with 10 the weight of a 42 is a plus... Maybe. Too heavy? Really? The diff between 832 and 1042 is what 8 oz, a half pound? A half pound.
I get its about where and how one birds. At least that ought to be the context we use in these conversations. Of course if someone birds in the back yard from the kitchen window less mag is fine. Here in mostly open terrain over water, cant beat a scope. Yikes. But 12s, 10s offer something over 8, thats worth trying to learn or train to make work.
$.02