There will likely be a number of BD-R disc designs that will yield 6+ year longevity. At this point I'm making my choices based on a combination of accelerated aging tests, reports here and around the web of which discs are starting to fail or are failing earliest, and my own experience to date. One misunderstanding I should clear up re TDK.
Don't buy TDKs. TDK came up with some of the best BD-R designs. Then, when it became too expensive to continue producing them in Japan, they abandoned their own designs. The BD-R in current TDK labeled packages is made by other companies, other disc designs, variable quality.
Fortunately, another media manufacturer, Falcon, chose to licence the technology and import the machinery and materials directly from TDK Japan to manufacture TDK's disc designs back in 2008. They even tweaked the design to make it better. They're still at it. Sold as Falcon BD-R and SmartBlu 25GB BD-R with TDK MID code. Falcon's quality grades range from seriously good to excellent. The lowest grade BD-R they will release from the factory is certified to burn 100% within the BDA book spec at rated speed. Their 4x plus grade is certified to burn within spec at any speed your burner is willing to burn it. They rank significantly higher than most manufacturers in keeping to these high standards.
Unfortunately, the long-lived Sonys can be a challenge to get. Sony has been packaging other discs in their spindles as well, and you would need to be certain that the seller was sending you 6x Sony NN3 discs. They can be found, but it requires a little extra vigilance to avoid finding yourself with a spindle of Riteks.
Two manufacturers have shown a desire to refuse to outsource their BD-R's and have shown well above-average quality control standards. Fortuitously, they also rank among the top in longevity testing. Panasonic and Falcon. When someone is looking for "the best", the outsourcing policies of most brands is making it easier every day to simply point to these two.
At their release, those 6x 100+ year Panasonics will likely only be available from sellers in the Japanese market, and at a guess they will be priced 2-4 times higher than the current 50+ year discs. Its up to you, but the current Panasonic 50+ year show every indication of getting you well past that 6 year timeline.
You're frustration is shared by many, and we're doing the best we can around here to lead people up out of that maze of bad BD-Rs
From my perspective, maturity of the technology is not involved at all. Its all about ever-shrinking profits in an ever-shrinking optical media market. We're not waiting for the tech to mature. Manufacturers' profit margins are simply making the good tech harder to keep track of.
We keep at it around here, though. We've rescued more than a few from the sound of that flushing toilet :bigsmile:.