I started with Disk 1 and worked my way up from there. I had to head out while the 3rd drive was syncing, and am on my way back to take care of the fourth drive. I was powering down the 4500 before I replaced a drive, just because I was very tired and extremely paranoid that I would fsk it up.
In between drives 2 and 3 I was able to access data on the server without any problems (reading and writing) so I believe it's all good. I'll let everyone know in about 3.5 hours, when the last drive syncs up.
As far as debug commands, I haven't found them on GuardianOS units. This was actually the first time I had to do ANYTHING with a 4500 and only got in about an hours worth of playing around and gettting familar with the GUI before jumping in....but the whole story isn't worth digging up at this point.
I'll take a quick look and see if I can find debug commands for it.