Using a 1000w light during veg is a complete waste of money. I grow a continuous garden harvesting every 8-9 weeks I use (4) four foot t8s to veg from clone/seedling till its time to flower at which point they get a 1000w hps. I too thought that using t8s or t5s was a ridiculous idea and a waste of money(at the time these systems were a lot more expensive than they are now). I chanced upon a a bunch of free t8 ballasts and said "what the hell I'll try it out". Not only did they grow about the same amount but the inter nodal spacing was a lot better and I didn't have any heat issues, oh yeah and my electric bill was about $64 cheaper. You can see the results for yourself I justed started a grow log the link is in my signature.

edit: Your correct about the difference in light intensity but this is only really needed in 12/12.