Chris,
I suspect the main reason for the 2720 is to provide a machine to compete numerically better with the B3030 Kubota and also provide a machine that can give better
PTO performance while in high range. I know for me, having had three different mid frame machines (4310 and two 3720's) the 3720 would do nothing more than would the 4310, but on my hilly terrain I found myself using A range almost all the time with the 4310, where I used B and sometimes C with the 3720. I have briefly used a 2520 on my terrain and really could do no meaningful work in B range. I think for someone like me the additional four horses and few lb feet of torque would really help. This does not really apply as much to those who live in flatter areas, as all these machines have ample power.
John M