I don't understand your point here...OP was asking is there a better battery or alternative to the OEM battery. Everyone and his cat will know that the OEM products are the safest because you pay a premium for the peace of mind, but are they the best? Maybe yes, but probably not. I explained above but then you twist the subject to talk about the unknown. Of course if you are unsure, you should not buy/use any third party parts, but if you know what you are going/getting, you can often get a better performing parts at a much more attractive rates from third party source...just ask anyone who are involved in car mods, or ask yourself the logic of why you buy a Sigma or any third party brand of lens to use with your camera.
You're talking about the R&D involved in the battery as if Sony themselves are heavily involved in this. No, Sony don't manufacture battery, in fact even their common NiMh rechargeable AA are sourced from Sanyo (now bought over by Panasonic) and rebranded. They merely present a spec and costing to their contract manufacturer and run some test of these batteries before slapping their logo on it. I'm sure many 3rd party battery brands are sourced from the same few manufacturers in China and they have much smarter guy in-house than most of us consumer to know how to deliver to the specs, because this is not rocket science. The problem comes when you have a few unscrupulous sellers who make wild claims about their batteries. Sony OEM battery is rated at 1080mAh, and if someone comes in and claim theirs to be 2500mAh with the same form factor and you fell for their b*llcrap, then you deserved to be conned. Just like buying a $25 LV handbag...you know the pain is coming.
To answer the OP, the bottomline is, buying original is often the safest route...but just keep in mind that just because they are slapped with a Sony logo, they "might" not be the best or give you the most value out there. A little background understanding will go a long way to help you decide which one you should spend your money on. If you're just buying just one additional backup battery, I suggest you spend the extra $$$ and go for the original. If you're a kiasu like me and/or don't charge your battery daily hence you need multiple batteries just for the "in case" situation, then it's worth some research before buying any 3rd party parts. I have 3 each of Sony original and the same equal amount of 3rd party batt for both my RX1 and A7R and switch them around, so far I cannot tell any difference in their performance...maybe time will tell. More importantly however, you should also invest in a good charger, be it OEM or 3rd party ones.