How much am I losing out - T8 vs T5

2 foot T8s vs T5s. the price difference is enormous, but how much am I going are my plants going to be missing it? I'm shoving as many tubes as possible in my space.

Not sure on the numbers but the way I do it is you grow with what you have always planning the next upgrade! I have a 4' 2 tube T8 that I got for 10 bucks. Does it kick ass? No. Will seedlings veg under it Yes. The light is not as intense with T8's IMHO not sure of lumen output but it will get the job done to a point. I think it may cost more to run them than T5's also. Grow em up!

Those T8's are awesome for lettuce.

http://www.htgsupply.com/Product-HTG-Supply-2-Foot-4-Lamp-PL-55-Tek-Lamp.asp

What are you going to use them for? If you plan on flowering with them don't expect a great yield.

just finished up a 200 w cfl grow over 1 plant, snagged about 3.5 off it.

I'd like to be able to flower with it. the only reason I'm thinking about moving from cfls is I think they put out more heat due to their compact size (tradeoff) vs tubes. also they are point sources which makes it semi hard to control their light footprint.