Look at this on the Samsung 850 Pro from Anandtech and quit worrying
Endurance Comparison of High-End SSDs Samsung SSD 850 Pro Intel SSD 730 SanDisk Extreme Pro OCZ Vector 150 150TB 91TB (240GB)
The other major improvement from V-NAND is the endurance. All capacities, including the smallest 128GB, are rated at 150TB, which is noticeably higher than what any other consumer-grade SSD offers. Moreover, Samsung told me that the endurance figure is mainly meant to separate the 850 Pro from the enterprise drives to guide enterprise clients to the more appropriate (and expensive) drives as the 850 Pro does not have power loss protection or end-to-end data protection for example. However, I was told that the warranty is not automatically denied if 150TB is reached under a client workload. In fact, Samsung said that they have a 128GB 850 Pro in their internal testing with over eight petabytes (that is 8,000TB) of writes and the drive still keeps going, so I tip my hat to the person who is able to wear out an 850 Pro in a client environment during my lifetime.
If you on your system where to write the a 128 GB disk full every day you would reach the 150 TB in 3.2 years. By then you would have a new computer anyway
While that answers the question about endurance, it does not address my other bold aspect: Do any of you have SSDs dedicated as an After Effects disk cache and allocate all of the space on that SSD to the disk cache?
In other words, do you use that SSD for anything else?
Sorry I am a Premiere person and know very little about AE performance issues. I do know that Premiere's Media Cache and Media Cache Files are very insensitive to read/write performance of where the files are located. I have actually run our PPBM benchmark on everything fro a SM951 to a USB 2.0 Flash Drive and not seen any difference in performance. AE and other programs probably are much different.
You might want to ask that question on the After Effects foruim