downgrading a patch level

In the 10.2.0.3 patch readme it states that I can downgrade the database with some downgrade scripts, then restore the 10.2.0.1 binaries and oracle inventory.

However, Oracle support told me I can't do this:

1. restore 10.2.0.1 binaries (oracle home install)
2. restore 10.2.0.1 oraInventory
3. restore my last 10.2.0.1 full backup.

so if I upgrade to 10.2.0.3 and something goes wrong and I have to downgrade. Do I have to revert back to my last full 10.2.0.1 backup or can I downgrade the database and thereby not lose data?

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