Hey Salamander, I would stear clear of the factory trailer. Everyone that I know has had nothing but trouble with them, unless they are heavily modified.
I guess that you could say that I'm a little biassed in this becouse I build trailers, BUT, the reason I got into building them is that there are not many good alternatives out there. I don't do it as a buisness, just a hobby. Interesting point, The last 5 trailers that I sold, all went to guys that used to run the Factory type Argo trailer.
The one you are looking at can be made to work reasonably well, but not what I would call great.
There are a few options out there, and I think that the best one for the back yard handyman is probably to just buy a pre-formed plastic tub, and build your own running gear.
Here is an example of one style that I build. I don't have a better pic right now. This one is for a quad. I like the tandem axle design, with the "walking beam" type suspension (very smooth ride). I like to raise the tongue at the front of the trailer, then drop it back down to the hitch (harder to hang it up on stumps,rocks, ect). I also prefer to build the tub out of Aluminium, it's easy to modify and fix if required.
These guys build something similar, and have some pics that you could check out. Of course a trailer built for behind an Argo will be wider than these model.
Tubs - Marathon Marine - Aluminum Welded Boats, Tubs, Decks and ATV Trailers - Quintrex Boats - Duraboat
One last thing, It has been my experience that swimming an AATV with a trailer in tow is ALWAYS a bad idea