Redsy:
A little late in putting in my 2 cents, but...
When I have a situation like yours, I 'hang' a sample fixture! Let it burn for a week, get opinions, a nod or nay from the guy that is signing the check, and it becomes the client's decision.
That said, the T5 fluorescents are making a big in-road into the warehouse market, along with multi-level and motion sensors.
Personally, HPS is not my prime choice, MH is, and check your info on the rated life, MH 400 watt is 20K hrs also.
Lastly, you know there is a retro bulb, MVR400/U/ED28/R, THAT YOU CAN JUST SCREW-IN? 20k HRS; $82 in WWG cat #392. (4WW46)
John
