iPhone iphone 5 high capacity replacement battery (gold) what's your thoughts ?

My daughters iphone 5 needs a new battery and I'm wondering if theses high capacity one's are any good. I have read a few things and there's a lot of conflicting feedback.

I replaced my Galaxy S3 with a high cap, gold battery and there is definitely an improvement in battery life but I don't know if that's because the old battery was plain old tired in the first place.
Alot of debate I read was regarding the price and people saying "If you could make a battery high capacity apple would have done this in the first place", but what would this cost apple manufacturing ?.

So , should I buy a genuine replacement battery or go for a high capacity battery twice the price ?

I was looking at these
2980mAh Ultra High Capacity Replacement Gold Battery for iPhone 5 ONLY from UK | eBay

3180mAh Ultra High Capacity Replacement Gold Battery for iPhone 5 ONLY from UK | eBay

I don't think I would trust a battery like that as it says its made in japan, not the best place you don't want your daughters phone to catch fire, which does happen.

I think you are better off with a genuine one. If you find yourself running out of power, then you could get a portable charger to see you through the day. Personally wouldn't trust the others

id give it a go and just keep an eye on it .. its the only thing i hate is the battery life