To me it comes down to cost. JD wants a bunch for their wheel weights. I put wiper washer fluid in my 3520 and it held it down really good. I put 45 gallons in each side. That was as much as I could get in them. I was getting 8lbs of weight for every $1.25 instead of $2.00/lb with cast weights, and I got more weight on there.
For what we are doing, fluid does not adversly affect most situations. In row crop farming, fluid is not the optimum setup. The reason is because of compaction. Radial farm tires are designed to flex under load and give you a larger footprint. The bigger the footprint, the less weight/square inch is pushing on the soil.
Fluid doesn't compress at the same rate as air, so if you put fluid in a radial farm tire, you are reducing greatly its ability to flex when going over the field, thus creating more compaction in the field and reducing yield. Wheel weights offer a much better alternative in this situation.
In our case here, that really doesn't apply, unless you are not wanting to put undo stress on your lawn or something like that. If that is an issue, then I would not go with fluid. I would use a
ballast box, because it is the easiest thing to remove. Wheel weights would be somewhere in the middle.
If wheel weights were a little less spendy, I would have them, because they are clean, out of the way, and reasonably easy to get on and off.
I can't see where they would cause any stress on bearings or any of that because they are putting their weight on the tire, not the axle. A Ballast box would put weight on the axle, but it should handle that.
Seems to me that any of these 3 choices will work. The issue is to find the one that best fits your needs and check book.