Roughly speaking;
MH 400w bulb ~ 30,000-36,000 lumens
4 Foot High Output 54w per T5 tube ~ 5,000 lumens
Without getting into light penetration after x# of feet, and more details, a 4 foot 6 bulb + 4 foot 1 bulb t5 fixtures (for example) give you the comparative lumen output before attenuation as the 400w HM..