I recently purchased a new L3200 with a 524 front loader and Long 4 in 1 bucket and a BH77 backhoe attachment.
I gave it great thought about the ballast box, but could not get past paying the cost of the box to hang on the back of my tractor to do nothing else but give me ballast when the backhoe attachment is not connected, so I opted for the 5' box blade with 5 rippers instead. Best choice I made so far besides choosing a Kubota.
I have used the box blade so much already, and it is only shortly over a month old. I am very happy to use the box blade for ballast. Ok, it may stick out behind the tractor a little more then the ballast box might, but I honestly think it is not by too much. At least not enough to make a difference to me.