You'd be surprised how hardy certain strains can be... some of them can even tolerate snow and freezing cold weather... just look for a very fast finisher like a paki chitral, hindu kush or pure afghani. Check out a strain called 'Erdpurt' from ace seeds, something like that might be perfect for your short summers :D
Definitely a different experience growing outdoor. You are much more at the mercy of the elements and your plants feel less like little science experiments and more like soldiers on the front line. The harvest you reap outdoor will be the fruits of your strongest plants, so outdoor bud always seems to be great smoke.
Both indoor and outdoor have their merits, but if i could grow legally, outdoor would be my preference.