I reckon if you can get them through the season in Europe you get quality, its the mold, pm, and bugs - which if you think is hard to control indoors - I was fighting every freaking day with my outdoor last year. The sun was shit the whole season, we had around 1 1/2 weeks of amazing sun in September (or was it October..?) and my girls just exploded. The resin you get on them is amazing, I got some of the best bubble hash ever from the outdoor. Smelled like sour sweeties (cola bottles).
I think what I am trying to say is, them just being outdoors and getting sun (it's still there, even though we don't see it often) is enough to get good herb. It's just the elements around them that need controling. But that's not impossible.