We had a case in the UK (sorry I can't remember the details) where someone lost a hand firing an OOD rocket (I don't know what age it was) - they can be really nasty things and are not nice to fire (as is any flare to be honest) - I'm sure if kept in a padded box (in the case of a planing 'bouncy' boat) that's nice and dry they can last 10 years - we've all heard stories of 20 year old flares being OK and I'm sure that the 3-4 life they stamp on them is based on a worst case scenario - I keep OOD smokes and red pinpoints, but not rockets - for the cost, even though I hope never to use one, I'm not going to take the risk.
Yes mate I have to admit rocket flares make me nervous, especially when you consider setting them off from a small rocking boat often with large amounts of fuel onboard.
I must point out to anyone who considers themselves to be safe because they have the minimum flare kit onboard to perhaps think again.
When smoke flares are set off in windy conditions the smoke holds very close to the water surface, I'm talking only around 1m high I've seen it. To actually see the smoke from one boat I was only 2 km from a sinking boat and honestly struggled to see it at all. The four people onboard claimed to of seen boats heading to port that didn't notice them waving frantically or the smoke from their 4 smoke flares.
When you see a flare being used for advertising, it's always during light winds where the smoke rises nicely into the air. Burn time is also quite quick, so for me setting any off while out around the continental shelf is a bit like peeing in the ocean to make the tide rise. This is why dedicated Epirbs are compulsory, plb's can be used but don't meet legal boating requirements.