I think we need a bit of input from Stephen now as he shoots RAW.
My thinking ...... may be completly wrong but here goes.
JPG = 8 bit
RAW = 12 bit
TIFF = link attatched
http://en.wikipedia.org/wiki/TIFF
So when RAW is converted to JPG our nice 12 bit image becomes 8 bit. Tiff on the other hand would retain the 12 bit. So a print from a TIFF file will retain all of the 12 bit colour. The downside of TIFF is file size. If I remember from early experiments when I got my camera these are huge in comparison to RAW.
This is where Stephen could help by giving an idea of the growth in file size going from RAW to TIFF on a 12 mega pixel camera. I will take my RAW file from this and do similar.
Don