zfs; adding vdev with same size and raid level but different layout

[Stefan Johansson]

Hello!

I’m running FreeBSD 9.3-RELEASE with a zpool in raidz1 with 5 2TB disks.
Now I’m planning to expand the pool with a vdev with the same effective size (8TB).
Would it be a bad idea to add 3 4TB disks in raidz1 to the pool instead of another 5 2TB disks?
What could be the disadvantage with such a setup?

Regards
Stefan