“wouldn't be appropriate to shoot the subject with the same lens, ISO, and aperture, varying the shutter speed to meet the same exposure based on the metering system of each camera.”
No... If you use the same Shutter Speed, Aperture and ISO under identical lighting conditions the exposure in each image from each camera will be identical. Using the cameras meter could cause the images to have inconsistent exposures making a comparison difficult. Even using a single camera the meter can change considerably between spot, center-weighted and matrix metering. The framing of the image can also cause inconsistent metering especially with matrix metering.