5D111 over 1D1V Benefit

Just looking for a simple clear answer from users of both systems. I use the 1DV mostly for sport and general stuff. I would like to venture into studio work. Will my overall experience of studio work be better with the 5D111 over the 1D1v. Will image quality be a bit better and will foccusing be better in low light.

I am in a position to have both cams but just woder if the outlay will improve my overall experience.
I would love to hear your experiences before I empty the wallet... or not.

Thanks in advance,

Mark