Hi :-)
You made a good buy :-)
The HiMD is a masstorage device and will work (normally) with the Amiga as a 1GB removable HD.
With the small price of the disks it will be a huge success I'm sure :-)
I will have one shortly and will make some tests with my USBized Amiga 4000 (see my profile to know more), I will let you know the results :-)
Oh, yes I work for Sony :-D but don't repeat it ;-)