lumens are for humans, its all about lux, and par (micromoles) lighting. t5s have come a long way so if your doing just a few plants, youll probly be good ive seen nice girls under t5s but you wont get pounds.
T5s are the way to go for efficiency,and you can get the lights closer.. I used plastic netting .. 2 inch squares.. scrog is the way to be especially if you aren't running h.I.d... Check mine out .. I have pics from right before screen to current..(day 23)12/12