Dean,
PI4 is being used with good results and just my opinion,should replace CW beacons altogether.Not many people are aware of this mode and how useful it is.
Software is almost too simple to use -
Of course GPS is required.FT8 would be interesting if it were to replace modes not so used in the U3S now.I have tried Opera recently and found NO ONE is there anymore.I fear that FT8 will end the same way soon as another mode emerges,but would like to see FT8 replace JT9 for selfish reasons :) JT9 also pushed to the wayside so I see a use for a FT8 beacon just because everyone is there to receive it now.Just check the decrease of modes used/not used,FT8 is winning,for now.
PI4 INFO-