Since you are considering roading the tractor between properties, I would suggest you take top speed into consideration. I don't know any of the lines except Kubota, but with Kubota BX with a 2 speed HST, its top speed is a few MPH less than the B line. I occasionally drive my 2920 to my daughters house because it is about the same time as loading it on the trailer and the trip seems pretty slow so it would be all the more painful on a BX.
Also it would be good if you had a place to store a Brush hog on the property or maybe at a neighbor's property. They are big and heavy and when I drive our little tractor across our other property with the mower up in the air, it really makes the tractor light in the front and want to bounce. When using that mower, I keep my FEL on for
ballast plus knocking down spiders that hang from the trees in the early morning.
We have the 3 acres we live on which is basicly a big yard and another 12 that is more recreational for now and is a mix of woods, brush, and about 6 acres of field grass. I would call the B2x20 a perfect tractor for where we live, but a bit undersized for "taming" the other property. I would prefer a little heavier tractor, but I trailer it about 25 miles, so that was a factor in the decision.
You may want to think about a rear finish mower vs the MMM. It would not be as good on the .4 acre you live on because it swings wider on the turns and is not as easy to cut around things as the MMM. But it is cheaper, even for a good quality, lots of choice of manufacturers, and easier to put on and take off than the MMM.