When you move your data over to your new hard drive, i would copy all of it (instead of cutting and pasting) just in case something goes wrong. Once everything is copied, I would delete all the files on the bad drive, then try to low level format, and that should be good. If you want to, there are programs out there that will do a more efficient job of formatting (writing 0s nine times over or something like that), but i cant remember the program name. I think you will be ok as far as Maxtor not reading the data. I am sure there is some license agreement stating that Maxtor will not exploit data on RMA drives... its just bad etiquette and practice. I think you'll be fine.
I think that companies first try to fix the drive, and if they cant, then they replace it. Sometimes you get a drive bigger than what you sent in
I have had that happen a few times with Western Digital.
Hope this helps.