Ben, I don't know what the cfs conversion is, but if you click on the gauge next to Embudo (on phateye) it will bring up a gauge in feet.
I ran it for my first time last week at 2.7ish. It was bony. My understanding is that at 3.0 it is about the best combination of rock and water for a manageable run. The run reminded me of South Saint Vrain in difficulty, but you are walled in and scout less because of it.
I have trouble ranking the difficulty, but I've been told that at 3.2 it starts to get pretty full-on, and generally only expert Class V-V+ boaters go for it. Above that it's every man for himself, and runs have been completed in 45 minutes.
I hope someone else can comment on the difficulty, but my guess is that if it looks like it will hit 3.2 or higher than to be very weary. At any water level a guide is highly reccomended.