Earlier we noted that perhaps the Russians have a better idea for dealing with the potential conflicting requirements of body armor and lifejackets for boarding parties. Now we have news of a similar British product.
Lets not forget the lessons of the drowning of ME3 Shaun Lin, Oct. 13th, 2010 during an exercise.
Chuck Hill's CG Blog 
Lin would have floated with the gear he had IF the CO2 cartridges had been installed. Carelessness and lack of attention will kill you every time. Just because it was not part of the inspection process does not mean it should not be done.
“Lin failed to properly configure his equipment, but his death was not caused by any gross negligence, recklessness or misconduct on his part, Brice-O’Hara found.”
If people fail to “configure” their equipment, how can it not be negligence on the person and his supervisor?
We had float-able flak jackets in Vietnam. The Navy used the on the SWIFT boats but the Coast Guard did not. My cure for flak jackets was to cut the zippers out and just button them over. Sinking in a flak jacket was thought about those many years ago.
Here is another source. http://www.foxnews.com/tech/2015/10/22/bulletproof-lifejacket-could-save-lives-at-sea.html