Initially, Rollies will be sold with separate Sativa and Indica strains. These are well known strains with effects that are also recognizable by regular users. Sativa is generally thought to have an uplifting and energetic effect while Indica is more relaxing and calming. These strains seem to have different THC:CBD ratios...
As mCig gets market feedback they will probably release THC e-juice products with varying CBD/THC ratios. It seems to me this would be harder to standardize using actual plants from different grow ops. JMO