We use Oris here on our Epson only.
With Oris, as with GMG, you have a ton of control over the profiles and characterization of the output device. Some RIPs just don't have the controls for such fine adjustments on the output. We can edit spot color definitions, custom designer inks, we can also "un-color" inks so that they don't print on the proof (like a varnish).
It gives us a better looking proof that very closely matches our Kodak Approval. We had previously used Black Magic on it (the Epson) and were happy with the results, but then found out about Oris at one of the proofing shoot outs several years ago, and have been using it ever since.
PS. as I was writing this I noticed Clod beat me to it, I'm a slow typist...
PSS. It looks like ColorProof Pro is about the same thing as Oris, GMG, just from Heidelberg.
