i start my seed in peat cups after paper towel germ.
I then move from peat cups into 1 gallon pots with a mix of 20% Perilite, 1 Part H.F., 1 Part O.F., 1 part cheap organic potting mix like black magic, or Miracle grow organic (without fert. just organic ).
After like 3-4 weeks veg, ( 1 week under T12's 3 under 400 MH ) I make my final move to 5 gallon pots under 2 600 HPS. for finishing ) The 5 gallon allow for more safety I.M.O. with the allowance of some extra root space, nutes already in the soil, ability to retain a bit extra water. I guess they take up a tad more space inside my tent, but I can go like a 1-2 weeks at times on just pure water, or a water superthrive light fish emulsion mix...... Only come the 3rd-4th of flower do I really feel nutes are needed and even then I run light.
5 Gallon even if the plant is cropped, or trained to stay shorter just better all the way around. Think of it as your house, you get bigger and move from a studio to a small house when you have kid.... sure it works but wouldnt you feel more comfortable in a 3-4 bedroom inside the 2 bedroom which would "work".