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Lenses contribute as much tone shifting as variations between models of sensors. I suspect it is not the 5D2 that is the issue, but rather your mix of lighting, your flash colour temperature and its consistency, and the variation in daylight colour temperature depending on time of day, time of year, latitude, altitude, weather, and nearby colour masses like grass, trees, brick paths, brick walls, coloured building siding, etc.
Use an X-rite ColorChecker Passport or their larger colour card. You can get proper colour temperature that way, and if you profile the light-lens-camera combination you can get perfect colour.
There are no magic formulas for the best results.
If the colours you are getting with the standard settings in LR (like Daylight) are not good enough, then adjust the colour temperature slightly. If that is still not good enough, take a close look at the tint and adjust the tint control. If that is still not good enough use the Camera Calibration panel. If you need more control, there is the tinting control in the Color tab of the Lens Corrections panel. And there is the Split Toning panel.
There is no substitute for mastering tools. You can make your own profile for your camera and your lens and your flash and your altitude and your conditions that will beat any canned profile.