Testing 8.0.1 - ZFS - Configurations

[newmember]

I am building a SAN for my vmware server.

I have 3 x 3TB drives.
I have 2 x 3TB drives mirrored and 1 x 3TB drive as a spare.

I do have 6 x 3TB drives in this server.
Should I consider moving to a RAIDz2 configuration instead?

I was thinking that the mirror would allow more speed to write to the drives than using RAIDZ2. The idea would be to have two iscsi connections connecting one each of the mirrored pairs of drives.

As well, if one of the drives fails I might loose my entire iscsi extent which would loose all my data, so I was thinking that I would reduce my risk of all my data.

Ideas please.

Thanks.