Id say the MX frame is a worthy contender if it wasnt for the potential haying. But you mentioned thats not likely. We can only guess at how unlikely it is....only you can answer it.
But the key biggest difference I see in your decision process is gonna be transmission choice. The MX is as big as you can go with a HST. So if that is a concern for doing all the other work....the next step up puts you into gears and shuttle of some type. But the MX is a great tractor for mowing and grapple work.
Made the exact same upgrade just a tad older.
L3400>MX5100
The capabilities are night and day different. I do the exact same work with the MX that I did with the
L3400. And would say there is really nothing that I do with the MX that I couldnt do with the
L3400....the MX is just faster and maybe dont require cutting a log down quite as small before grappling and loading.