I have no experience with M111, except for a tree that has a G.11 interstem. It is definitely dwarfed relative to what M111 should be. I live on a 150x80’ suburban lot, so no room for many M111 trees… My point of view is also framed by the understanding that this might not be my forever home, so I didn’t want to do a lot of raised bed plantings that I would just have to tear out prior to selling the house. (Not sure if my fruit trees would be a ding against us in selling the house.)
There are people with lots more experience here than I. I just have the particular experience of needing to grow on wet soil due to growing in my yard.
I like G.935, but have had the discussion that Geneva roots might be prone to viruses transmitted from infected scions. I have a hypothesis that the problematic G rootstocks will trace back to having an Ottawa 3 parent, which is also virus susceptible.
I believe if you are doing your own grafting it might be a good idea to steer towards G.11, G.41, and G.202, which don’t have that virus-susceptible parent. If you are buying from a nursery, and not adding extra scions to make multi-graft trees, then there is probably less to worry about from most of the Geneva stocks.
Geneva roots “should” be relative resistant to root rots due to wet soils. The selection procedure specifically was designed to kill seedlings flooded and inoculated with Phytophthora.
So, this is sort of a lot of blabbing, hopefully it is useful info, even if most of it is from reading.