I agree with the "no specific wording". I admit its subject to debate, but if you look at half of a divided raceway, it seems like it could meet the definition of "an enclosed metal raceway with a removable cover.....".
If surface metal wireways were required to be listed as such, that might put an end to my argument. But I don't see that in the 2008 Code.
Sometimes I wish this rule would allow some calculations relating to how heavily loaded the wires actually are, but sometimes I guess its best to just keep it simple.
The divider is used to separated signal and power in a
single raceway. A raceway has all sides open to free air. The reason a divider is allowable because signal wiring is not expected to carry significant current and therefore not to cause much heating. Placing power conductors in both sections violates this assumption.
Further computer rooms loads are almost always 24/365 loads and generally the equipment in the room costs vastly more that in others settings (except bank vaults and perhaps jewelry shops). We have an internet hub in a local school in a room about 10x16 feet. The contents cost more than $300,000. Looking for ways to "squeeze" the
Code is not a good idea for such a setting.
Modern business is highly dependent on computer operations. Disruptions can be very expensive, and lacking proper backups and recovery planning, can destroy a business.