If I were you... since you are upgrading from 9 to 10... I would definitely go with Live Upgrade.
Basically you can split the mirror, Live Upgrade your system from Solaris 9 to Solaris 10 on the inactive leg. Boot to the new environment and if something goes wrong the back out plan is really fast and straight forward.
You can read more here:
Upgrading from Solaris 9 with a Root SVM Mirror to Solaris 10 with a Root ZFS Mirror with less than 10 Minutes of Downtime
I haven't followed that process but it looks good.
The good thing about LU is that the downtime is minimal, and you still preserve the old OS untouched...
Still you will need a console connection and an installation CD in case you run into problems.
Another good Idea would be to replicate the environment on a box, if it local much better, try and document the procedure and then go for the production box, but I know that that sometimes is asking too much...
Good Luck!
Juan