I'll go the other way on the advice. I had a BX and went to a B. We have a bit under an acre that I mow on our property, it's flat. But, like you, I do things off our property, and I use the FEL and 3ph for stuff.
The BX is the smallest real tractor you can buy. I believe it's deliberately sized so guys can buy a tractor without their wife going "hang on, that's a tractor." So it looks like a large ride on more than a small tractor.
But, the front wheels are a bit too small to take a lot of load - if you lift a lot with the loader you can flatten them. It's also hard on a relatively small front axle. The rear wheels aren't large enough to get height, and the overall machine is deliberately low. So the 3ph doesn't have the range of motion you'd normally have - it doesn't go high enough and doesn't go low enough. And the geometry on it means it lifts a lot less than you'd expect.
In short, a BX is massively more useful than a ride on mower, but it's quite compromised as a tractor. The B2301 is essentially the same size on the ground - basically the same length and width - but taller with bigger wheels. There's also not much difference in price. But there's a lot of difference in capability - the 3ph lifts double as much, the loader lifts 30% more. It runs at 2800 rpm instead of 3300 and with a bit more capacity, so it doesn't sound like it's screaming away quite so much and it has more torque (it's still a small motor, so it's still running a lot faster than say an L2501).
A B2301 will turn in the same space (it has split brakes), but in terms of not marking your turf, probably turns a bit worse. But I went from a 54 inch deck on my BX to a 60 inch on the B, and I can actually cut into tighter corners because the mower deck sticks out further - I have curves on my decking and I used to scratch the decking timber with the rims on the BX when I wasn't careful, whereas the B is a good couple inches away from the decking cutting the same curve.
If you're going places around the neighbourhood to work for others, the B top speed is a lot faster than the BX - because it has that 3 range gearbox. Driving a mile down the road on a BX would be super painful, but doable on a B.
If you're planning to do some work for hire, then the B will be able to do a lot more. Also, a B allows you to add a backhoe at a later date, whereas a BX you buy a whole new machine (too hard to add a backhoe unless it came with one). If you're planning to do work for hire you may find you want a backhoe at some point. And the position control instead of inching valve is worth a bit if you're doing 3ph work (with that box blade).
I will say that the whole work for hire thing often sounds like a story guys tell their wives in order to buy a tractor. It's not clear how often it really happens. I've never pretended I'd do work for pay. I do lots of stuff to help neighbours, I mow our roadside for a good distance either way (neighbours are old, none of them really up to doing it any more), and I mow and maintain a few acres of local reserve land. So I'm getting plenty of use from the machine, and the B is much better at those tasks than the BX was. But I'm clear I spent that money so I could have a hobby, not because it was going to make money for us.
One thing to watch out for is that I do think the B cuts up the lawn a little more if I'm not careful. It's a bit heavier (like 15%), but bigger wheels mean similar ground pressure. But in 4WD it does seem to scuff the grass more - I generally don't run in 4WD unless I really need it.
When I was looking to upgrade (I looked for about 2 years) I made this table, which is still pretty up-to-date:
A table I had made for BX and B01 when I was looking. I've seen a few questions on differences, so thought I'd post the full table including the B50 series (and now L2501 as well), because lots of people ask about the differences. Really no question or point in the post beyond contributing...
www.orangetractortalks.com