But... If you're thinking of cloning the drives individually and then adding them back in, it will not work as far as I can see on any card I've used. In theory it could be done within the RAID principle (byte for byte image with a little side work), and then you could just extend your volume with a partition editor. Unfortunately, in practice, most RAID cards won't let you adjust parameters of a single array volume at such a low level, they only understand create, delete, extend, convert in most cases. Convert won't be of any use because it's used for converting from a RAID 0 or RAID 1 to a RAID 10 (or to a RAID 5 on some better cards if you add enough drives).

Now, there is an exception to this.... Many RAID cards will allow you to replace a drive on a RAID 1 or 5 with a larger drive, so if a drive dies and you can't get that small a drive, you can replace it with a larger one. This feature would be used as well to upgrade an array to larger drives. The downside to this is that it will take forever to rebuild, and your RAID will run quite slowly while it's rebuilding. If your RAID card is smart enough, it will allow you to increase the size of an array volume as long as there is enough space left on the array to handle it. In this case, you would, as in the above example, use a partition editor to then extend your partition on the array volume.

My RAID card on my big machine allowed an conversion from four 36GB IBM Ultrastar UL36LZX to four 73.4GB Quantum Atlas 10K II, then from there adding 12 more Quantums to make 16 total. It took a four days of swapping a drive every night when I left the office and telling it to rebuild, then adding the other 12 (across four channels BTW) and telling it to expand the RAID, then a day to extend the volume after all that was done.

Just remember, there's a big difference between a $3000 6 channel 512MB Ultra160 SCSI PCI-X card (hey, it was 2001), and a little $25 SIL3114R5 SATA job.

Why not image to the higher disks and then cut max LBA to match original capacity?