that was my plan, i jus wanted to make sure i wouldnt be "wasting" any light
Na, it's a good idea... and as mentioned above those are not the only spectrums you can chose from.. there are all spectrum bulbs that have a bit of both.
I like to have the blues (6400's or so) and the yellows (2700's or so) mixed up because I ONLY use blues for vegging.. no light in existence I have ever used keeps the growth so tight and lush. And then I introduce the plant yellows when I flip to 12 12.. the color of the light 'they say' is more akin to what a plant wants to flower under .. although I have flowered under blue cfl and MH's with completely desirable results... in fact I much preferred some of the MH grown grass to the HPS version of the same genetics.. there may of been some weight compromise.. I didn't notice.. I didn't care, I'm only personal use and there was plenty.
Whatever any of that is worth.. as your skills improve in growing and you learn the most important lesson (leave them alone) and apply it, you will find light is important, but the plant doesn't need nearly as much as one would think to get great harvests of mature fruits. Just keep em short and LST.. those 4 ft tubes in mixed spectrum will be PLENTY to do some incredible yields in a small space if you use your space and train your plant correctly. PLENTY of light. (although a cfl on the sides right the last few weeks of flower in addition to the top lighting, sure tricks a plant into filling out better under low light environments.
Good luck mate~!