(this is from memory so bear with me if version names are not exact. I also wanted to get some thoughts down, but will revist with more clarity later if this goes anywhere)
I use a Canon 300D. I have used Phase One CO since the first Rebel version.
One of the version of CO (3.6/3.7 ?) used a new profile system (i.e V2) to help correct the 'yellow' issue. I also use Magnes profiles for the 300D. First the v1, then the v2.
What I have found is that by using the same WB/tone setting the new camera profiles are far more magenta and greens have a red/magenta cast to them. There was discussion back around the time this changed that WB/tone settings will need to change.
I am looking for some others experience in how this affected them. I am consisently finding that images I developed pre-V2 are much more green cast, with more natural greens. With V2 I am finding that tone needs to be reduced to minimize the magenta cast.
Anyway this bring up the question on the 'default' white balance presets for the camera. For example 'Sunny' is 5150/4. This tends to be too magenta - do others notice this? Is this 5150/4 no longer right to be close to the 300D 'sunny' profile?