I have a DX-1G and the YS120. I haven't tried them in water yet, but DS-TTL does seem to work reasonably well on dry land. Granted, some of the exposures aren't consistent, but it seems to cope well under a range of circumstances. The main problem it seems to have is with macros, when the camera is so close to the subject that little light from the flash is needed. This can lead to the strobe not firing. The solution is to ensure that ISO 80 is selected, or that the aperture is closed down. I'm looking forward to trying this out in Sharm, next week.