I want to start here by saying how much I have always respected gwdixon's advice and the courtesy he portrays in his posts. G. W.'s thoughts have been very helpful to me on several occasions. I hope G. W. will not take this post as being disrespectful to him, as I surely do not intend any ill will.
Looking at the page linked below, Kubota indicates that B. P. is correct, all BX models, regardless of 2 digit or 4 digit number have the same hydraulic pump. With the addition of the subframe, a 4 digit BX with a Woods BH6000 is just as capable as a 2 digit BX. Lee Brown has a number of times pointed out that the ROPS is smaller, but every TBN member who owns a 4 digit BX with the bh, and has posted about it (including me), has stated that there have been no real issues with this.
Tractors | BX Series| BX1860/BX2360/BX2660/BX25