Hi there! I know it's been over a month since you posted but I just did this *today* and YES it is possible. I have the same G-RAID and I pulled the two HDDs and dropped in two WD Blue SSDs. They're not as fast as NVMes -- I'm only getting around 500 MB/s read+write -- but it's better than the previous speed and most of all it is QUIET. No more damned drive clicking. Note: you will need adapter trays to convert the 3.5" drive sleds to 2.5". I found a cheap model on Amazon made by Orico, works great.