The main problem with having 250w on one side and having 600w on the other, is the plants on the 250w side will get jealous.
Now what will happen is it will start with jealousy, but it will progress much further throughout the grow. Before you know it you'll wake up and the plants on the 600w side will be missing limbs and leaves. And if you're not careful and leave a full watering jug, or any bottles of nutrients in your tent, the plants on the 250w side will take and overwater the 600w plants (plant death by drowning) or they will go the sly killer route and poison them with nutrients.
It's brutal man, plant on plant crime is on the rise.