Good Vibrations
Actually, this was on dispaly at the Brighton SAR conference several years ago. Then it was a German company who had developed it and had a working version on show in the hall. The demo was actually quite convincing. The jacket they had looked like a standard LCJ - i.e. the load carrying jerkin rather than an LSJ [life saving jacket]. Their claim at the time was that in a training environment you could teach someone to hover quicker because they were using more senses than you would normally use. The only thought/issue I had was that they would then only be able to hover with a vibrating jacket rather than use the same cues a normally trained pilot used? However, they had a fix for this, by alternating the sorties so that you [i.e. the brain] used a combination of techniques and data to produce a hover.
I think it might just work - as long as you didn't have a doppler runaway or some malfunction in its ability to detect when the hover was actually achieved. Overwater would be interresting? I guess now they would use GPS but that would be fixed point not stable hover relative to water or dinghy etc.
Still convincing demo!