Interesting perspective on energy density: the amount of electrical energy you can get out of a LiCo/LiMn/sim lithium battery is still only about 1/10th of the energy you get from burning the same size or weight in wood.
https://en.wikipedia.org/wiki/Energy_densityOf course burning the lithium batteries might be another story, and wood varies
a lot I believe LiFePO4's might be safer in regards to avoiding catastrophic sudden energy release, but they're not as popular. It would be nice to see the industry try to change over (I'm assuming the cost differences are mostly due to popularity). Many products use under-size or low quality cells to begin with, so I don't think the capacity per unit volume differences would be mostly noticed.
FWIW I keep my spares in a metal box on my shelf that I've lined with fibro. If I ever do have a problem I hope this might help me contain it. And I keep the hell away from any product with a lithium primary (eg CR123), I've read too many horror stories on CandlePowerForums regarding permanent lung damage and HF acid mist.
I don't think I've ever seen nor thought of a C-tick on a battery here until now. I'm so used to expecting them to be uncaring imports. Sidenote: be wary of the difference between the two types of 'tick' you can get, they look similar to consumers but mean very different things.