Requires time and ... 2 bars for a real evaluation
It's not so easy to choose the hardware for a Synology NAS. The hard disks recommended by the manufacturer being almost impossible to find, I had thought that the use of a SSD cache would improve the access time and limit the wear of the platter hard disks.
When I installed the cache, however, I discovered that it takes ... 2 to get both write cache and data protection. A single cache (RAID "basic") is just supposed to improve read access to data, which is not my priority, my only applications (or "packages") that are permanently solicited being those that ensure backups (TimeMachine, synology Drive).
I have no vision on the gain. I put 3*** because you can't put nothing and for the LDLC service which is always flawless. I'm going to try to buy a second SSD before I increase the number of PCs that back up to my NAS.