I live on 2 acres and manicure a little more than 1 acre. I would have loved to have a larger tractor, but it would have been absolutely silly on my lot. Also, the size of my lot requires a certain 'nimbleness' that larger tractors...even the Kubota B series, which is a matter of HUNDREDS more than the BX and not quite twice the size...cannot offer.
If I had a mountain home/lot, some pasture somewhere, or ANY other reason to have a larger tractor, I would. Without that justification, my BX blows the doors off of any other mower I've seen in use in my neighborhood.
For me, anything bigger would have been silly. Less, in my case, was better.