G Drive 3TB Thunderbolt replace drive

Hi, I just bought one of these drives off Ebay. It looks well used but is described as fully operational, and the void warranty label is intact. In intend to use it as a secondary backup for a large photo library.

I understand this model has a high failure rate, so I intend to swap out the 3TB HDD and replace it with either a 4 or 6TB HDD, or possibly a 2TB SSD.

Two questions. Does the high failure relate for this product relate to the HDD, or the enclosure itself?

And, does anyone know the limit of what HDD or SSD this enclosure will accept?

The label references are: OG03125 / GDRETHU3EB30001BDB

Thanks very much for any help.