Just my 2 cents for what ever it's worth. If all you need the second tractor for is to mow 3/4's of an acre and tow some stuff around would it make more sense to buy something like a Cub or JD garden tractor? I love my BX for the tough work but I still use my 25-year-old Cub 1210 for mowing and dragging things around. You can pick up a good Cub for under a $1000.00
I got my mid-90's Kubota G1800S (S=4 wheel steering) for $2200. The hours were unknown, as the hour meter died at 53, but it runs fine. It has a 16 HP 3-cylinder diesel engine, so its in the same league as the
BX1500 on power. My particular one has a 48" deck (which is a good thing for my property, as I can get in smaller places with it), but the 54" deck is more common, and the
G1900 (same tractor, but with 18HP) usually comes with a 60" deck. The 4 wheel steering is great for going around obstacles, and turning around in smaller spaces. At the time I bought this, I debated selling the
B7100 that I had at the time, and just buying a BX to do everything, but it is nice to not swap out the deck and loader. I now have a
B7610 ( a little bigger, and can lift more than a BX) for most non-mowing duty, including snow removal, and moving firewood (which it does better than a BX would, because of its larger size and lifting capacity), and use the G1800S for mowing , and towing my 5x8 utility trailer around the property when doing cleanup. I'm making a debris fork for the B7160, so having two machines will be much better than one for all jobs, as I'll be able to move the trailer with the
G1800, and load it with the
B7610.
So, in summary, the
G1800 is as good a mower
for my purposes as the BX would be, for a lot less money.
I think the big differentiator of a BX vs. a good garden tractor (not talking about box store crap here, talking about Kubota G or GR series, or the JD's not sold at box stores) is the 3PH hitch, 540 RPM PTO, and FEL capability.
Of course, my G1800S is a mid-90's machine, and new price on the current high-end GT's can run as much as a new
BX1860, used prices also can be high as used BX's. The advantages of some of these machines (over the BX) in mowing is lighter weight and tighter turning radius (in the case of the
GR2110, or the JD's available 4WS).
So, if you want a dedicated mower (and maybe to save a little money over a BX), you might want to get a used high-end GT that can do a little more. If you want another good all-around machine that can do it all (maybe, just without a loader, or even with), then go for the BX.
Keep us posted, and post pictures of what you get.
EDIT -- OP -- I just noticed in your post that you wanted 4WD. The
GR2110 is 4WD, as are some of the high-end JD GT's.