Thanks for comments. I also found the previous thread
Having all the types of safety gadgets has a certain appeal, but how much is enough? Why not two or three of everything?

We just priced a full offshore set of pyrotechnics (good for about 3 years only) Gets close to a backup EPIRB.
I am inclined to go for the 21st century technology rather than the Victorian

Of all the survival accidents I have read about, I have yet to find one where a rescue depended on a flare or rocket. Most do on radio/EPIRB devices