This is just my experience with the pairs I own. The BHs are 9.5D (on the SD last) and the SJs are 9.5E but on the 461 Classic last. My previous posts explain why that is. The 461C last is supposed to be like the standard SJ last only with a more upturned toe. Going by my boots in front of me, I would say the SJ last is roomier. What all that means is that yes, I think your 10.5D SDs should fit fine.
I don't know how much insoles adjust the fit, other than the heel area. I can say with 100% certainty that you can make much more adjustments by varying your sock thickness. Also, something to keep in mind is that wool socks (at least 75% wool) are excellent at wicking away moisture, so don't assume wool=hot sweaty feet. I said I don't wear my SJs in the summer. That isn't because they make my feet sweat, it's because they look kind of goofy with board shorts and Hawaiian shirts.
Thanks again Andy B., very helpfull info!
Love the visual of SJs, bored shorts, and Hawaiian shirts… whoever could pull that one off could rule the world.
Thanks, that’s reassuring. I just can't wait to put them on, there gonna be so nice!