The law here is simple. Growing is illegal but having one female plant is "the lowest prosecution priority". In other words, as long as you don't have kids and don't sell/share, nobody will care because it's not worth the paperwork. Have a spare room turned into a plantation, then you get shafted. Be like some of those caught in the last week or so with over 1000 plants, well, you'll find you won't be getting 4* hotel food where you're going. Ultimately, the golden rule applies, "Don't tell and mask the smell" for if nobody has the chance to say anything to the Boys in Blue then they won't be knocking on your door.
As far as going "full spectrum", there's no question that there's a psychological effect, but when you can physically feel the inflammation vanish, bits that were so warm you could almost fry an egg on them suddenly cool like you've hit them with an ice pack, then there's no doubt about the "physical" side of things, so for pain control there's no question regarding the physical effect and that's backed up by medical research. But, as you say, some strains don't have the same analgesic effect, and that's where the minefield is entered as many for sale are good for SOME things but not others, and a critical part is how it's used. I've found that out the hard way, shall we say, as my pain comes in various forms and the wrong strain can dull some forms but that means the others are amplified so I end up no better off than had I not consumed any. Too much in one hit can do the same, same as "medibles" can do the same. So it's very much trial and error, but that's part of the fun in life.
CBD, on it's own, also has other known effects, which do affect me thanks to the diabetes as it has been proven to be a VERY good aid regarding blood sugar control and diabetes itself thanks to it's anti-inflammatory properties, basically the effect is that it reduces vascular inflammation associated with metabolic syndrome which is associated with Type 2. And it will reduce blood sugar levels, hence why we get the munchies, as well as being a vasodilator which has obvious benefits regarding circulatory problems linked to diabetes. It's not a cure, obviously, only lifestyle changes like I made do that, but it is an aid and is why the Israelis have actually been developing CBD based medications to help treat Type 2.
I say all this because the whole MMJ thing is far more complicated than people realise, there's no "magic bullet", but that applies to "conventional" medication as well as I've lost count of the number of different toxins medications I've had the joys of swallowing over the years. What I do know is that CBD on it's own will reduce symptoms with me, but sometimes that "little bit extra" is needed which is why I've tended to go for the higher THC strains and then temper that with CBD as things can change on an hourly basis with me just with the slightest wrong movement. The biggest issue for me is how quickly my tolerance to anything rises so I don't get a choice about using as little as possible if I want it to have the right effect for as long as possible, and is why I take a break from any pain medication, whether it's weed or pharma, to bring things back a bit because I know how quickly I have to up doses if I ain't careful and higher doses of things like Codeine, or stronger, is never a good idea.