replacing drives in a terastation or readynas? benefits of tape in a nas?

Has anyone created a 2-disk RAID0 or RAID1 array in a terastation,
readynas, or similar, and then pulled the drives out, put them in
offsite storage, and replaced them with 2 new drives?
If you haven't, do you even know if it's possible?
Basically i'm trying to simulate the benefits of tape in a disk to disk
solution.
In detail, I'd like to make 2 seperate volumes in the device.
I want to use volume #1 for incremental backups, then when a weekly
full comes around, do it on volume #2. Repeat every week until volume
#2 is full with weekly backups (1 months worth for the sake or this
example). Then I want to take the 2 drives of volume #2 out, put them
in offsite storage, and replace them with 2 brand new disks configured
for the same RAID type, then start the process again. In this scenario
I would want to rotate about 3 sets of 2 disks in and out. So then i'd
have 2 months worth in offsite storage and up to a month onsite.
Eventually i can add another set which can contain quarterlys and so
on.
What do you think?

Thanx,

-Tony