I just built on this mobo using 2x16GB Crucial Ballistix Sport LT 3000. This RAM uses Micron E-die, in my experience it's very overclockable, second only to Samsung B-die (I've never had those, but they are quite touted in the community. I Ignored XMP and overclocked using DRAM Calculator to 3600 CL16 at 1.35V. It's really quite simple to adjust the timings, the calculator lists exactly what values to input in the BIOS.

While I'm not sure what performance loss you get from running single channel, my thought is that it'd be noticeable, and the drop from 3600 to 3000 may not be unless you're gaming. However