Cat,
Read your manual for the loader. JD says that a minimum amount of ballast would be a loaded ballast box AND either loaded tires or a full set (6, 60lb weights) of rear wheel weights.
A 200cx on a 2320 can lift about 1/2 ton at the pins, so you have to add that amount on the rear to counter balance.
However, you have to take into account that wheel weights and/or loaded tires do not provide the same function as a loaded weight box. A weight box, suspended on the 3pt arms actually decreases weight loads on the front axle as the ballast box uses the rear axle as a pivot point like a see-saw. The front axle on the 2x20 series (or any of the xx20 series for that matter, or else Deere wouldn't call for a ballast box) is not meant to work with a loader lifting maximum loads without the counterbalance of a filled weight box in the rear.
Now, don't get me wrong, I use my loader without a ballast box a lot of times for light loads, (wood shavings, lawn debris, large bulky items that weigh under 300 lbs) however I have weights and loaded tires. Whenever I am going to lift anything heavy, on goes my Portland filled ballast box.
As far as the 4 in 1 for the 200cx, the smaller JD one goes about 600Lbs, that being said, you would have about 400 Lbs lifting capacity which I think you would find very limited. There are other manufactures that make 4 in 1's that weigh less but in real world use, you have to get into the construction grade equipment level for them to work like they are meant to. (Now I know I'm ruffling the feathers of the guys with the 300 and 400 CX's out there but I ran a Case 580 with a 4 in 1 and an articulated wheel loader for a few years, there is no comparison between construction equipment and farm loaders on the xx20 series)
My 2 cents,
Tom