As a sales person looking for the best value for the customer on ballast I recommend the cast weights. You only buy them once! If there is a need for more for the type work you are doing, then go to the liquid weight. For many tire designs the liquid hinders traction so it's not the best system for adding the ballast but it is the least expensive initially.
To have a little pucker factor once in a while will make for a better operator, just like testing your car out in the snow if you have it by putting it into a skid on ice to test the tires.
To heavy, and you pay every day to move it!
It only takes one flat tire and you have to buy the liquid again!!!!