Where that kind of setup tends to fall short is in holding items when production machining and you rely on fixed register points (the step in a collet, or step chuck, for example).. Mind you, I'm not suggesting that they don't work well----far from it. It's just that there are times when a thou makes a huge difference, and collets generally won't register close enough to hold the tolerance. I'm not speaking of concentricity, but holding lengths. Soft jaws are repeatedly reliable for that operation. I've run countless production jobs by both methods and have resorted to a fixed stop in the spindle of a machine in lieu of relying on a collet with a step, or collet stop, when collets were better adapted to the job at hand. Small parts run at high spindle speed is a good example. Do keep in mind I use a Hardinge-Sjogren collet chuck. A lathe equipped with a lever closer is more likely to repeat, but only when each item is held to a close holding diameter, wavering no more than a thou.
Harold