I just goggled the Kubota BX23. It is quite a bit smaller than a John Deere 4200.
I have a 4200 with fel, mmm and a number 7 hoe. It was used with 900 hours when I got it but there has not been enough time spent on it or others of the size to make any comments other than I really like it and so far it impresses me.
Not sure I'd put it that way..A little bigger in size..3 more horsepower. Also, it appears that it came in 2x4 or 4x4..Manual or hydro. The 23 only comes one way..4x4 and hydro. Physical size doesn't mean much unless your using large impliments. My BX23 runs circles around my previous 8N, which was probably 3 times the size. All in what you're going to use them for.
I moved a tri-axle load of limestone last night and 25-30 heaping one ton dump truck loads of dirt on Saturday...Not too bad for something this size.
Half the weight, half the loader capacity, half the 3pt lift capacity, half the rear tire size, half the hydraulic flow.... probably half the year adjusted new price too. So its half the tractor. Approximately.
But sure, a BX23 is a fantastic little machine if thats what your needs call for. I'd rather have the Deere 2210 in that size but that is also half the tractor.