@Max.

I selected the battery on capacity-about the same as the 20 cell NiCd , 3000mAh, promised 20C and for this case, local availability. And after reading the UK reviews, you have 1 negative review, and 2 positive ones, and the packs have a good rating overall. So were is the 50% bad review rate?

As I'm happy with the Turnegy and Zippy LiPo's an LiFePo4's in our machines. Up to now they do exactly as promised.
And yes, I expect a dull pack everytime we buy a new one. But that's why we try to buy packs in the local warehouse, makes the warranty easier to claim.
Here's a cheaper one in the same range.
If you follow the rules as the FRA gives them, and take good care of the packs, there shouldn't be any problem. Of course, packs still will fail if the shocks are heavy enough, or when an axe or disk goes trough them. But that's the same for every battery.

If you're really concerned about safety, buy the LiFepo4 packs, a tad heavier, a tad more expensive than LiPo, but still lighter than any NiCd or NiMH pack, probably even cheaper per mAh.