[berkut]

With respect to the 737-8 MAX though, although in this case it's nothing to do with MCAS, doesn't the 737-8 MAX have smaller radius trim wheels than previous models (so less leverage)?

So in theory, trimming might be more difficult on the MAX than previous 737 models, especially at higher speeds (where there's more force on the control surfaces that would need to be counteracted in the case of runaway trim).

[slacktide]

The trim wheel on the 737 MAX is identical, down to the part number, to the trim wheel on the 737 NG, which has been in service since 1997. The trim wheel on the 737 NG was reduced in diameter by approx 1/8 of an inch compared to the 737 Classic, which has been in service since 1982, in order to give adequate clearance to the “new” CDU (data entry keyboard for the flight management system). Since the trim wheel is around 10” in diameter, a 1/8” change would have a negligible effect on trim forces.