Are you wanting to resize the actual raid or resize the partition on the array?
Once the array is built and you have partitioned it, it's just like a regular hd in most respects. You could use something like partition magic to resize the partition. Although most in here would tell you not to do it. I've used it before without problems.
Best thing to do is back up all your important data to be safe...but you already knew that
of course I do one thing at a time in Partition Magic
resize > reboot > move > reboot > resize > reboot ect
and never use the merge function
multiple tasks and the merge option seem to be where most folks get hung ip
then they make it worse by hitting that power bitton and of course they dont have the rescue disks
regarding backup
well you should always have good backup