I have ordered an Innovations Microflate from Wiggle and I am wondering how safe these canistors are to carry. How should I carry them? What would happen if one burst? I am probably going to carry them in by CamelBak (M.U.L.E.), but how sturdy are they?

The only soft part is the bit that gets punctured when you screw the canister onto the inflator valve. The rest is sturdy alu which is pretty much bombproof. I wouldn't worry.
The worst thing that could happen is you somehow perforate the bit that you puncture, and the CO2 will be released.
FYI the same canister is used in aircraft lifejackets, somehow time-ex canisters end up in my possession.

But what would happen if I fell on one and it popped? Would it perforate me or bust my lungs via blast? There's a lot of gas in there...

Are co2 inflators any good?I looked at `em.
honest answers please!

AL
No you are fine, most good canisters come with a safety cover over the nipple. It would be very unlikely that you could force one to deflate without using the specific adaptor/ inflator. FOr info I used to carry mine wrapped in a rag but only to prevent them banging and clinking when they knocked together.

Why carry two I here you ask? Because despite all the advertising about control valves and partial use etc etc, in practice these are one shot wonders. Great for racing where time is everything! The 2nd one is for the emergency when the inflate doesn't work or control valve freezes open and you lose all your air (CO2 actually).

PM
They are good as long as you understand the limitations of the above, put it this way on general rides I carry a mini-pump (and patches) but it depends on your attitude to the ride (ie do you have to complete each ride in the fastest possible time or is a puncture a good excuse to call an early lunch/ snack break whilst you get a ribbing from your mates!!).

CO2 is heavier than air. It'll increase the weight of your bike.

There has to be a market for N2 or Helium cartridges.

Hmmm, you'd need better tubes though as He will leak through butyl.

AP

Yeah, the molecule is too small and passes through the polymer.

Mind you, The wife and I had Helium filled balloons at our wedding recently. I thought they'd all go flat really quickly, but they were still inflated about three days later, so there must be a special butyl/rubber out there.