A bit of history. I started looking for a riding mower in spring 2006. At the time all the JD stores downplayed the 100?? or whatever series and all they wanted to sell were the $5K - $7K riders. I got to the point where I needed to cut the grass on a property I bought - was too cheap to spend the $5K - $7K and just bought a Craftsman 54" that was on sale. So that temporarily solved the grass problem but with winter coming I needed to solve the snow removal problem. So I was looking at 2305 / 2320 / 2520 with FEL and practically everything else on the market as well. In addition to comparing equipment / test driving / reading etc I was getting quotes for various combinations. Everything seemed expensive.
In the midst of all this I found a used Honda 6522 diesel with snow blade - made the owner an offer and much to my surprise he accepted. So now both the grass and snow problem was more or less solved.
Somewhere along the way I decided I was entering a second childhood and that a tractor with FEL / MMM / Backhoe was required. I arbitrarily or otherwise set some minimum criteria. I wanted a 72" mower, FEL that could lift 1 cubic yard of dirt and BH that would dig at least7.5' One or more of those criteria eliminated the whole JD 2xxx series and quite a few models in the other colors.
To make a long story short, I purchased a 2008 JD 3320 / 300CX / 72" 7-Iron & BH. I used that for 3 years and it basically did everything asked, including lifting a 2,100 lb skid of tile off my truck. Granted it only lifted about 1" but I did get it off the truck.
So there I was happily mowing / digging / moving snow with the 3320 - hot and dirty in the summer and cold in the winter. During winter 2010 my son and I had to do some work where we borrowed a couple of big Agco cab tractors and then my son bought a cab tractor. I started thinking - heat in the winter is nice. Air Cond in the summer would be nice.
I started looking at my options and considered that additional FEL lift might be handy and priced out 4x20 cabs and 5083E Limited.
Between the second childhood thing and increased FEL capacity, I pretty much decided a 4720 Cab would be a good compromise, although if I recall the 5083E came in at a slightly lower price point.
I actually called the JD store a couple of days before month end and suggested we could haggle on a final selling price. He said that wasn't the best time and that JD often had better pricing in a month or so.
At the time I bought the original JD the Cab and BH were not compatible options. As I was looking around at all the above options, I had found a JD 3320 Cab with FEL / BH and made an offer that was rejected. However, the same day I called the JD store, the 3320 Cab owner called to say he had reconsidered and would accept if I was still interested.
I bought the 3320 Cab, switched my MMM to that unit and sold the O/S.
So to recap - I was very happy with my original 3320 and I bought another. Both have done everything I've asked, except for a couple of times where FEL capacity could have been greater. A lot of people say the 3x20's feel tippy - they probably do, but I put the wheels in the wide position, I'm aware of the limitations and so far have not tipped it.
I can't fault the 3x20, but at my stage of life, if starting over with a clean sheet, I'd probably buy the 4720 Cab or the 5083E Limited- not because I really need that much tractor - just because I think I'd like one.
Owners who have had both series could comment, however, I think the actual cab size is the same on both 3x20 and 4x20, so that is not a factor.