I agree with Mr. MFRED's comments. I've got a 593 just slightly smaller than the 596 and have had good luck with it. Those Perkins engines are dependable. Have a cab model, and as stated is a good basic machine.
Have heard good things from some friends that have a 5400's, they really like the Dyna-4 transmission. Having driven them a couple times I really like that transmission as well. I would probably have a 5400 except for the cost.
Noticed the three steps like Mr. slowzuki when getting in the 5400 cab. That didn't bother me to much, as usually I'm in the cab for several hours for each outing. If I was getting in and out a lot, my knees would let me know.