Re: I'm puzzled..
The rdx cartridges are slightly modified 2.5" drives, but the cartridge casing and plastic container give a little bit more shelter from damage and liquid, the proprietary 'similar but not quite sata' connector is recessed.
They've got a read-only switch on the cartridge.
Swapping the drives can be entrusted to any conscientious employee, as with tape, to bring off-site each day, without drive letter issues etc.
Some of us are really annoyed by small business LTO tape drives failing us when they are needed.
The 3K entry pricing for LTO4 is just too steep for many; let alone having a second drive in case of failure.
With RDX, it's only the media that needs to be replaced when the backup set grows, the media is more reasonably priced now than it was.
Transfer speed is lacking though.