I have a 1602D, I'm 5'10" and have a little trouble climbing on and off, but once there I'm comfortable. As to the power, it'll depend on conditions, but 72" might be stretching it a bit.
If you're mowing flat ground, not too tall and not in too much of a hurry, no problems. But since the 2000 is phsyically a bigger tractor, will you have any issues with tight spaces? If everything is wide open, maybe a bigger one would be better.