As I said the clearances with the chains are tight, but with careful installation they do work on my 6284 (the manual makes no reference to chains). I would recommend that if you purchase chains be sure that you can return them if they won't work. Remember also that you can expand or reduce the diameter of the side chains which was a big factor on my tractor in providing the needed clearance when installing them.
I keep a careful eye on the chains to be sure that they don't shift to where they can potentially cause damage, but after carefully and securely installing them they never moved on me. I limit their use to snow, ice, and soft ground. Given the rough ride the chains provide they certainly are not subject to pavement or high operating speeds.
Short of purchasing an entire new set of wheels and AG tires for all four corners the chains made the difference between having a very useful tractor for processing and hauling firewood in the woods in deep snow vs a tractor that is stuck in the barn until spring.
In some cases I agree that you can fill the FEL to add weight but I wouldn't recommend it for extended use. The additional loading placed on the FEL frame and the chassis by suspending weight this way is substantial. Front suitcase weights are the best way to add weight.