I bought the SOS light a couple years ago, based on advice from a USCG officer I know. I do like it and this is what I was told. You have to buy new batteries for it every year and keep the receipt with you to prove they are new. Also, make sure not to leave it in the on position and run through your battery power.

I have never had to use a regular flare, but I'm told they make quite a mess on the deck and can even burn upholstery, so you have to hold them over the boat side when lit.

I already had a flag so to me the light is the best.
Rickerd