We're not quite on the same scale as you but pretty much the same chore list. Upgraded from an 8N Ford to a Kioti CK35. Ford has sentimental value to us & almost no dollar value in our market so we fixed it up and keep it as the "little tractor". Already had a couple projects where we had them both working.
The picture below is a couple weeks ago - My son & his Girlfriend are on the Ford raking up round bail remains, I'm on the Kioti grappling up the piles, and Dad is on the 4 wheeler making sure we do it right. :laughing:
What will the littler tractors do that a 70 hp won't do??
Fit in a tight space.
If you're whole tractoring world is part of the great wide open then never mind.
There are a bunch of times I wished we had gone bigger. When I'm pulling the 5' RC between the barn and a fence and I'm about to rub the barn with one tire and fence post with the other is NOT one of them.
Will I miss the one of the little tractors if I only have a larger on my hobby farm??
I'm willing to bet you're going to run into something where you want to haul, spread, or dump something someplace that the big boy won't fit. Then it's back to shovels & wheelbarrows.
I know I don't need 3 tractors, but should I keep one, and which one??
My opinion - the 4wd and FEL makes the 4200 the keeper of the current two.
If you're dead set on selling one or both then I also second the advice to go ahead and get the 5075e - then see if & when you really do need a smaller tractor and which one. It's not going to cost you anything to keep them.
Best of luck whatever you pick.