It seems to me the studies in the posted article are from a time when marijuana was dramatically 'weaker' than what you get today.
At least in SF the legitimate dispensaries do a good job of informing you about these things and finding the strains that will accomplish what you want.
For more modern up to date science backed information on CBD see projectcbd.org
CBN is not a primary cannabinoid, it's a breakdown product of THC and simply indicates how old or stale the cannabis is. It's primary effect is grogginess and general unpleasantness so you want to avoid it as much as possible.
Any dispensary that says CBD is good for insomnia is simply repeating long disproven but widely spread information.
Also, intentionally-high-CBD strains are under development [1]:
"A high-CBD cannabis strain was developed in the 1980s by David Watson and Robert Clarke, American naturalists who founded a company called Hortapharm in Amsterdam to pursue their goal of developing plant strains for different purposes. (The day Watson and Clarke became expatriates is the day the U.S. lost its lead in the field of cannabis therapeutics.) In 1998 Hortapharm sold its seed stock to a British start-up, GW Pharmaceuticals, which has since developed a strain that expresses 97% of its cannabinoid content as CBD.
GW plans to test its high-CBD strain as a treatment for rheumatoid arthritis, inflammatory bowel diseases, psychotic disorders, and epilepsy. It is now in Phase 2 trials to determine the dose levels to use in clinical trials involving people. GW mixes its high-CBD and high-THC strains in a 1:1 ratio to make Sativex, a plant extract formulated for spraying under the tongue that has been approved in Canada and elsewhere to treat neuropathic pain associated with multiple sclerosis. CBD evidently bolsters the pain-killing effects of THC while moderating its psychoactivity."
[0] http://www.nature.com/news/2010/101001/full/news.2010.508.ht...
[1] http://www.counterpunch.org/2007/07/14/who-s-afraid-of-canna...
It's very discreet and pretty effective, esp. if you are looking for a more CBD non-thc delivery method.
Unfortunately these are a local Denver product right now from what I can tell (my friend in SF can't find them their yet outside of driving to Berkley); so it might be difficult to find outside of colorado. They also make a variety of cartridges including Sativa, Indica and Hybrid.
I've switched to using this most of the time esp. outside the house, or when the kids are around. When you exhale there is hardly any smoke either and I've seen people smoking these at bars openly. I haven't been so bold even though I have a red-card, things sure have changed fast, at least in Denver.
Edit: Also, the high effect is minimal, esp with the Sativa cartridges. Much more of a body, pain reliever type effect.
Edit 2: Cartridges are rated for around 300 hits, and at 40 dollars per that works out be a pretty cost-effective solution from a cost standpoint too. This might not be as effective as a mj joint however; I would be curious to know if you get one if it's more or less effective.