The reason I would consider it is that yesterday I needed a reasonably long, thick gouge to turn the wall/floor intersection area on a deep bowl with an overhanging rim. My half inch gouges has swept back wings so re-grinding them to a steep standard grind would have meant grinding off at least 1 cm of tool and then grinding back to my preferred profile when I'd finished the project. I only really need 1 extra gouge at the moment which would set me back around £30 - obviously much cheaper then this system. quote]
In this situation ie getting to the floor area of a deep bowl I sometimes use a shielded ring hollowing tool such as the Hamlet or Munro. These are designed to cut on the side of the grain and with a cross grain bowl that's exactly what you have in the floor area. The advantage of these tools is that they can cope with large overhangs on the tool rest. You can then put a shear cutter on the end to finish the process.
Regarding the changeable tip tools I heard mention that sometimes the tip doesn't line up with the shaft so consequently you get a step. This can be a problem when trying to make a flowing cut and the step catches on the tool rest interrupting that flow.