The OM-3 is fine ergonomically, for me at least. The thumb pad on the back is very comfortable and balances the body very well. I held off buying one for a while because of ergonomic concerns but in practice it’s been great.

I'm super happy with my OM10 mark3 and z9. the first is super fun to use and gives a really satisfying shitter kachunk when you shoot and the z9 though a chonker makes adjusting stuff easy having a billion buttons