After hearing about all these stories and wanting 3rd party batteries myself I put up a thread about the same thing a few months ago.
Reading the recommendations I bought 10 batteries from a seller called 'loo100us' on eBay to see for myself.
There are no complaints about the finish of the housing, the internals are tidy and they last as long as my OEM batteries.
I've been using just two batteries which have been cycled each week for the past three months and they have not exploded or exhibited any peculiar behaviour.
Sure, there are shockingly bad 3rd party batteries, but there is no special voodoo in making good Li-Ion batteries. The technology is mature and they can be made very cheaply and well - of course, this is not so good for the Earth.
I'm not at all connected with the bloke behind 'loo100us', something to keep in mind though.
I see you're up in Glasgow, if you pop me a cheque for £6 I can send you a battery to try.