As I posted before, we fitted and trialled the Omni-direction Approach Path Indicator (ODAPI) on the Leman 'A' in the Southern North Sea in the early 90s.
The main issue was the lack of initial visual pickup because the beam was swamped by the ambient lighting. It might be better now because more powerful LEDs could be used. It was also a mechanical device (rotating mirrors I think); if built now, phased arrays might be used reducing the size and and mechanical complexity - it also needed a power supply.
There is also the issue of siting; to be omnidirectional it ought to be sited at the centre of the deck but that is somewhat impractical. The beam should also permit flight down the beam to the deck (with a threshold crossing height) but that would require siting above the deck level (or behind for a single azimuth approach) and still would not fit in with offshore performance profiles.
All-in-all a positive report was filed but the device was returned until problems had been solved. Flying constant angle curved approaches was good handling practice. Most pilots did not think it had much merit.
Jim