I understand your not wanting to downgrade to ArcGIS Desktop 10. I have reverted my desktop back to 9.3.1 so I can actually be productive.
However, I upgraded my server to version 10 and it works much better now than the 9.3.1 version(s).
Since it is running on a different box, different versions are allowed. Version 10 services are still available to 9.3.1, so didn't "break" anything.
Unlike other "upgrades", this one is pretty painless. Just make sure to save your configuration files first so you don't have to type all the server info in again.
Just a thought,
R_