[Nikker]

I just can't seem to figure out where you are coming from on this. My first question is, why would you plug a device with transfer rates in the 20-40GB/s range into a SATA3(6Gpbs) port? Next is although we can wax poetically on what exactly is the best case for every ones use cases how are you going to guarantee that the micro controller will work the way you want it to? Databases with properly configured indexes will retain the important data in RAM with out further modifications, and again how would you ensure that the records you feel should be cached are cached since the small micro controller would barely have the resources to analyze the data stream to begin with.

Lastly if you do care about data retention during power outages and sags then you would likely want an APC/backup battery. Even though the data stored in the SSD/RAM hybrid might have enough backup power to flush to disk how about the data that is currently in RAM waiting to be flushed as well?