As a Journeyman Wireman, I can safely say, that although it may be a cunthair more expensive to run the T5's(which shouldn't even be noticable), you will get a greater coverage than with CFL's, unless you run a few of those 250W equiv's you are talking about, but one can NEVER go wrong with spending probably the same amount of money on say, a 400W MH and veg the living shit outta your 5-6 plant grow, which I surmise is probably in a smaller apace like a closet or something... With a nice coat of flat white paint, and 5-gal buckets over a short drain-pan and grate, with a sm. sub pump for drainage, plumbed into a 5-gallon "office-style" water jug, I run a 400W MH and a 250W MH along with 2-250W HPS in a 4' X 2' closet and can easily illuminate and bathe anywhere from 5-11(right now) nice plants in intense H.I.D. lighting, coupled with a cheap-to-operate little home-made CO2 gen, and some good fans, and I regularly crank out .91 grams per watt on my 1,150W mixed spectrum system... I'd definately always run the numbers, and as long as you can control your heat and ventilation, and it's not going to double your electric bill, then, I'd reccommend doubling, or tripling, in my case the suggested amount of lumens per sq ft, and watch the bounty... But, you haveta be careful and watch your stretch, as it can become overwhelming if you do not prepare accordingly, with lights that are easily raised or lowered at any time, stakes, a trelis system, or ScrOG or SOG type ststem...which is oftentimes very necessary, especially if you FIM, and/or super-crop, as I do...