Andrew, as I understand it, there is a 48" rockhound that has no bucket and simply rakes the rocks inside its housing until it is full. Then, you lift the rockhound and leave a pile of rocks to later pick up with your loader bucket. There is also a 60" and 72" rockhound that include a bucket to collect rocks. These models allow you to lift and transport the rocks to a pile where they can be dumped. However, this process is not a lift and dump in the traditional sense because it is recommended that you keep the bucket low to the ground.
I think you would have no problem with the 48" or 60" rockhound, but the 72" model might be a little large. It would probably work fine if you had the 72" 3PH model, but I think you would prefer the 60" model for mounting on a loader. I believe the 16LA loader can handle any of these rockhounds, but certainly I would not look at lifting the 72" model anymore than 2' to 3' off the ground. Full of rocks, it will be right at your loader's maximum lift capacity.
For any of the rockhounds, I think the best setup would be to have the rockhound on the 3PH instead of the loader. I'd keep my loader bucket to pick up piles of rocks left by the 48" model or pick up rocks from the piles created when dumping the 60" or 72" models. In my opinion, the 3PH rockhound with a normal bucket on the FEL is the preferred setup. Especially since if you put the rockhound on the FEL, you have to drive backwards to operate it.
I've never had a rockhound or seen one operate, but my guess is that they are a lot of work even when they are operating properly. They also seem to need a pretty skilled operator for best results. If I had rocky soil, I'd consider buying a rock bucket for my loader as an alternative to the rockhound. To me, the rockhound is something used by a landscaper to prepare grass seedbeds around new construction houses or even refurbishing existing lawns with rocks. It's not really the type of tool you'd use to clear acres and acres of land of small to medium rocks. Just my opinion. . . .