Any hard case study of the durability of SSD's not just the reliability? 3.5 HDD's have been around for over 30 years. I ran a small IT network for 17 years and had only one HDD fail. This was a 20 workstation office running tower HDD's 24 hr a day without the sleep modes back in 1990's. We were able to recover the data from the platters of one fail HDD since information is magnetically recorded on the surface of the platters. [NOTES: Also, RAID error detection before failure. I purchased many HDD's replacements not due to failure but to upgrade bit size. There are millions of junk HDD's that work fine in junk shops that are useless due to their capacity not because they failed.]
I have had many SD cards fail without NO warning and NO recovery opportunity whatsoever. Also, those small laptop HDD's (including the small backup portable drives) have a horrible durability rate. SSD's are relatively new and growing in capacity to the family of desktop towers in business with no 30 year durably records to compare to 3.5 HDD's. My recommendation is that if you are building a new desktop tower and want to utilized the new SDD technology, use an EPDM server that stores on HDD's or cloud based storage. This will protect your data. Mirrored RAID (SMART disk monitoring) SDD's can cause multiple failures. I would NEVER archive on a SD, laptop drive or those small portable HDD drives. I had already two small HDD's fail on me in the past three years.
"SSDs can be used as cache for a RAID volume. Two HDD disks mirror for reliability, augmented with an SSD cache for speed. This can be done easily with ZFS."
Because SSDs are relatively young in their product lifecycle, a high-capacity SDD is significantly more expensive than a similar HDD. However, many desktop computer users are taking advantage of the SSDs' reliability and speeds, while still using an HDD for primary storage. This can be achieved by upgrading your computer with a dual-hard drive configuration. In this instance, a lower capacity SSD is used as a boot drive. It will hold the operating systems and any other major applications that you use frequently. Other data, such as secondary applications and assorted files, get stored in the HDD where more space is available.