I,ve seen them used to devestating effect over the last couple of years, sooner or later I suppose I,ll get one, large and small.
In the meantime I'm still using the one I made years ago from something similar to a large kinder egg.
Never lets me down, done me equally as well as the guys with spombs but just falling short on distance compared to a spomb.
The spomb is good but on rivers they have their shortcomings only being able to free the bait on the surface, Years ago I made a baitdropper that can deliver a payload of free offerings anywhere from the surface to any depth decided on by the angler.
Great for barbel where bait can be released just over the top of the fish without spooking them.