From reading the change log it seems that CGMiner will support Butterfly Labs Monarch's, but when I look at the Monarch specifications, it says it only supports BFGMiner. Why is that? I'd prefer to stay with CGMiner for my Monarchs.
The "relationship" between bfl and cgminer has always been awkward and strained. They've never directly supported running cgminer on it and they employed the fork miner author to write their official driver, though they then sent us devices to write drivers for them. Cgminer supports the monarchs fine, even if BFL doesn't say so.