The best answer to this is to do it and see if it works for your needs. Normally deform bones and control bones are separated to make it easier for both expanding the functionality of the rig and to troubleshoot problems. There is no rule that says you have to separate them and in some cases it's preferred to have them share bones.
Hey Samy,
Yes the spine in this character is advanced - but it's mainly just a few tricks so the 2 halves of the spine can bend from the middle and then have 2 set of controls.
I don't think you would be able to do what you have mentioned though.
But I don't actually remember what your Hard Surface model looks like.
You might be better off to design something more along the lines of the spine that is used in Rigging the Wrangler in CORE Rigging.
This seems like a better approach as you will have more of a tangible example to adapt.