I would say the quality difference would make up for all the extra space, not to mention that you need a faster hard drive to pull uncompressed.
But as Rafael said there should be no lose in quality if you are converting it correctly. The only thing you what to change is the codec. Resolution, frame rate and field dominance needs to remain the same.
Once you get the workflow done things should move along. The key is getting it right before you start the edit.