the more light the faster it grows which means the faster you have to prune it
2 "watts per gallon" will give you adequate growth for most of the crappy plants available in calgary. Anything brighter and they'd grow like weeds and just make pruning a daily chore...
plus anything brighter than that and you get into CO2 and nitrate dosing... if you need nitrate lemme know I have 50 pounds of the stuff in the garage