My first bigger battery PV was a Riva from LF about 9 months ago. Both batteries still work but I can tell that they don't last as long as they used to before needing to be charged again. I also have 4 650 mAh eGo and 1 900 mAh eGo batteries of various ages and they are all still working well. I'm not sure if the Riva batts are the same as the ones sold 9 months ago or not.
I think my batteries are lasting a long time because I rotate them. I use 2 for a day then they go on the charger then to the bottom of the rotation. I know that is not reasonable for everyone but I'm just sharing what is working for me.
I think in general that battery life and reliability are relative to use and care. I clean mine each time they go on the charger and any time I notice
juice in the connector. While the batteries are sealed, juice and condensation build up can have an effect on performance and charging.
There will always be a few duds from the factory but I never worry about anything I buy from LF. I have never gotten a bad product from LF and I know they stand behind the stuff they sell.