In my humble opinion – as a dentist that does mostly cosmetic work - the king of shade taking is a DSL camera that has a ”Custom white balance” and have that picture displayed on a calibrated and profiled monitor. Really just making the camera and monitor color accurate.
This takes 15 minutes, and just one time. 2 minutes for the camera (WhiBal G7 White Balance Reference Card) and about 10 minutes on the computer, doing the calibration and profile (X-Rite i1Display Pro).
You can debate monitors, but the Dell Ultrasharp, (Adobe RGB gamut) monitors are awesome for shade selection in dentistry. Dell calls these monitors PremierColor. The U2413 is one of the models.
Experience has shown me that I see color differently, using a photograph (with this setup),than using my eyes in the operatory. If the lab tech and the dentist use this system – it’s just perfect. Just my 2 cents.