Single Channel Memory, AMD Zacate (Fusion) Question

I'm mapping out a low power bedroom HTPC build and at this time the AMD Fusion platform is where I'm headed.

For those who don't know, Fusion motherboards only support single channel memory (64-bit memory bus) and not the usual dual channel mode (128-bit memory bus). The Fusion board I am interested in has two DDR3 slots but since it does not add the benefit of dual channel when populating both slots, I am considering a single stick of 4GB RAM to keep power requirements to a minimum on this low power build.

So here is my question for the memory gurus:

Is it worthwhile to go for the fastest/low-latency stick of RAM the motherboard can take in an attempt to recoup some of the performance loss due to the single channel limitation?

For example, how would a stick of 4GB DDR3-1600 CAS7 RAM in single channel compare performance-wise to a DDR3-1066 or 1333 CAS9 2x2GB kit run in dual channel? What about 2x2GB DDR3-2000 or faster in single channel compared to a low-end kit in dual channel?

I'm also not convinced that a single stick of RAM is the way to go. Looking ahead, a 2-stick kit would be easier to transfer to another system that does support dual channel, or sell on fleabay. However, I'm looking to have the least amount of heat and power in my setup and I can't ignore that 2 sticks pulling ~1.5V each would not be as ideal as a single stick pulling half that. Additionally, for optimal heat dissipation one stick is better than two since the airflow is more restricted with two sticks in close proximity to one another. Comments on this matter are appreciated as well.

Thanks in advance.