I veg with a 4 foot 2 bulb HTG fixture 10,000 lumens and amazing compact growth. I use blue spectrum bulbs. Keeping the light close keeps plants down(which I want) and makes inner branches explode. Controlling growth is easy since if you want them low, keep the lights 3-5 inches away. If you want a little stretch maybe for some LST, lift the T5's a foot and a good stretch will occur in 2 days =D
Good luck