Definately worth it. I suffered when all my kit was dropped as an underslung load from a Sea King in the Adriatic. Then again I have never seen so many stereos lost on a sngle palnet according to the compensation claims from the 50 or so 'affected' lads.
I recommend PAX insurance, good kit cover and fully understand servicemans needs. Also you can update it for household or storage if you need.
Also they do a year long travel insurance. Sounds a waste of money but if you get deployed (and that happens quite quickly these days if gaps are found) you are covered. Why? Well on the run ashore you may only get MOD help up to a certain amount. They also do Winter Sports coverage and I found them cheaper than the rubbish normally found. also they have an allowence for hoildays cancelled due to service reasons, all you need is a letter from the CO. Very useful that one I can tell you.
You can pay monthly or all in one. No I don't work for them but have used them for the last 10 or so years. Never had a problem.