Fan Speed Controller questions??

I'm looking for a controller that would be able to handel 23watts at 250CFM and it's going to be turned down to around 150CFM so I would think it would be using around 18watts. I was thinking the Nexus 4-fan Speed Controller NXP-201 would work? What do you think?

On a single channel or spread out across multiple channels?

I was thinking of just using one channel, can I put one fan on two?