The moisture control has coco peat in it I think. It's one of those things that some people love and others hate. I for one have used MG soil, the "regular" kind, and it worked fine. If that's all you can find it's great, it's not evil like a lot of people make out to be.
However I have noticed much better results when using Fox Farm's Ocean Forrest. The Fox Farm grown plants are growing faster, have tighter node spacing, and are generally more healthy looking.
P.S. Great choice on the Northern Lights. That's my next purchase. NL has been kind of forgotten with all the new fangled brands coming out but it's still around for a reason; it's a damn fine smoke that's easy as hell to grow. It also makes a great base for hybrids.