If you have two drives that are in a pool and you are wanting to repalce both, you only need a docking station if you aren't duplicating the pool right? I am doing something similar but I don't have a docking station. My plan is to make sure that both drives getting replaced have all the same folders/files (pool duplication). My initial thought was to remove the first drive to be replaced from the pool (all folders files still in the 'one-drive pool', power down the computer, physically replace the drive I just removed with the larger one, boot back up, add the new drive to the pool and wait. After the pool has completed writing to the new drive I'll go throught the same process with the second drive to be replaced.