I am using the 3:4 setting with 333MHz Samsung memory at stock voltage without a hitch. I would like to use ECC memory, but am not willing to try it again until someone verifies ECC is working.
Unfortunately there may not be a SPDIF in. No one has attempted to solder the connector on the back yet. No one has figured out whether the current drivers will add the SPDIF to the control panel if it existed. No one has hooked the MediaXP port 'out' to the 'in' connector to try it. No one has verified that the chipset used was the E revision or later that could actually do SPDIF in, although obviously the review machines had revisions that would do SPDIF in.
Since review machines had SPDIF in enabled, I am still hopeful.