Ubuntu Servers :: How Do You Enlarge Raid 6 Partition

I am trying to grow my array to make full use of my drives. I have a raid 6 using mdadm on my home server. The array used to consist of 6 1.5TB drives when it was created. Since then I've been replacing the 1.5TB drives with new 2TB drives. And now I have replaced the last 2 drives.

When I added the first 3 disks I did not use the whole disk for the raid partition but rather made it the same size as the 1.5 partitions. As it turns out this may have been a bad idea. (But it gave me another 3 partitions of 500GB that I turned into 1 disk using mhddfs.)

Now I'm trying to grow the array. I've been testing in a virtual enviroment on how to do it but I cannot find another method than this :

1) fail 1 disk.
2) re-partition the disk with the size of the whole disk.
3) re-add the drive as a spare.
4) start the now degraded array to let it resync.
5) wait quite a while. (aprox 5 hours)
6) start again from step 1 for the other disks.
7) use mdadm with grow command to enlarge the array
use resize2fs to fill array to max size

Now although since this is a raid 6, I keep some redundancy but I still worry about degrading the array so manny times and rebuilding the whole thing. I mean I read the thing out 3 or 4 times over doing this.