I respectfully disagree with the advice about getting a flail mower. They are very expensive in comparison to rotary mowers or cutters (3 to 4 times the cost), and there are three categories: light duty have knives to cut grass, heavy duty have hammers to break, not cut, heavy/stemmy material, and medium duty is in between. Size is not related to light, medium, or heavy duty; you can have a narrow heavy duty and also a wide light duty model. Flails are designed to work in areas where there are bystanders. Rotary mowers and cutters can launch rocks and hurt people. Flails will not launch projectiles. Flails also have numerous knives or hammers to maintain. A light duty flail will indeed give a fine cut on lawn, but will not cut heavy material. A heavy duty flail cuts stemmy material well, but does not have the fine cut on lawn that a light duty gives. Rotary mowers just have three blades to sharpen and brush hogs require little to no sharpening at all on the two free pivoting blades they typically have. If you want to mow lawn and also cut 2" sapplings, you really need two implements, regardless of whether you go with two rotaries, two flails, or one of each. I know of one single implement, the Woods RM990, that will cut both; it is a hybrid between a rotary mower and a rotary cutter, and requires around 80 PTO hp, so that is out of the question for a BX and also for use on a bigger tractor on your soft sod.
As to the 48" brush hog mentioned, I know of no heavy duty brush hog in that width. The 40" Gearmore is heavy duty and is the exact width of the BX body (42" body, 40" cutting swath). I find that ideal when cutting brush between trees; if the tractor fits, the RC is going to match the tractor chassis going through the same opening. The wider the blade on a given RC, the more the torque is dissipated. The HD blades, being massive, build a lot of inertia to break stemmy material. The medium and light duty rough cutters have less mass in the blades, thus less inertia, and depend on sharpness and relatively unimpeded torque to cut material. On a heavy duty model, the weight and inertia in the blades break the material that they hit.
Some have suggested getting a B rather than a BX, and while it's correct that the very lightest B is not too much heavier, I do not see it having the versatility of a BX. It is true the B has higher clearance, but the converse of that is that the BX has a lower center of gravity.
For mowing several acres of lawn, you might consider a really wide RFM rather than the OEM MMM. Again, going with a heavier tractor would not be good on that soft sod, and while the BX might take more time than a big tractor, it is going to be much faster than the garden tractor.
In my own opinion, the
BX25 is the correct tractor for the situation you describe.
