5309,
I have a Frontier GM1072R on my 2520, and I have lots of hills (20 degree side slopes). The mower is over 800lbs and tends to drag the rear end of the tractor around, even with three wheel weights per side and the loader frame mounted. I also need to be in 4WD all the time to have enough traction to move the mower. If you have flat property, this may not be an issue for you.
If I'm mowing really tall, thick grass and going up one of these slopes, I find that I will have to back off the "go" pedal a little to keep the RPM's in acceptable range, but otherwise, the tractor seems to have enough HP for the job. Not sure how this translates to the 2320 which has slightly less HP.
I'd sure be tempted to go with the 60 inch mower unless I really needed bigger for some reason. The 60 will cover your tracks and might be a little lighter and easier to maneuver.
Best of luck.