I can only speak from experience trying to get something in that is useable. Experience of a lot of wasted time, multiple scanning systems, and contacting and working with multiple vendors...
My opinion? I was much less than impressed with all but the X-ray. I will never forget ( or get back) the hour I spent with one hotshot salesman who scanned a part for us and showed us how we could get a spinable color picture that showed height changes as colors..... No dimensions were associated with the colors, but more towards the blue meant higher and more towards the yellow meant lower..... I kept asking for the data in a measurable format so I could measure dimensions, and he kept offering that useless spinnable color picture that couldn't be measured.
Did I mention not cheap??? It's thousands of bucks per part.
When somebody digitizes, you get a lot of points in space in a software format that is written for the measuring device. Buy the measuring device, get their software. With SOME of the measuring softwares, you can measure and edit the model produced by the scan. If a straight line scans in as a curve (which it frequently does), or there is a small dent or scratch in the scanned part, you can straighten it or fill in the dent with the measuring device software. That scan is then converted from the proprietary software to a software format usable by CAD or CAM (computer aided machining) software.
But when that scan is sent to your CAD or CAM system, it comes in as a solid shape and nothing more. You can spin it around and look at the shaded detail, and that's about it. You can't fill a scratch, fix a dent or straighten a line.
You can say "ooooo, pretty" but you can't do anything with the solid- like measure a hole in a ring...... Why" because the part has no"history" of being built, and the CAD/CAM software can't find the center of the hole or the edge or the radius. It's just like trying to measure a smoke ring with calipers. You can see it, but you can't touch it or measure it accurately.
You can move the calipers around so they look like they are in the center of the smoke ring hole and sorta look like they are at the diameter of the hole, but you aren't measuring anything you can touch. If you take those "guess" dimensions and make a real part with them, you can measure the part you just built, and you can place the built part on the "smoke ring" to check for accuracy.
That's what happens when a scanned part comes into a CAD/CAM system. It's a "smoke ring" that is viewable but unreadable by the CAD/CAM system. The CAD system parts are built step by step as a mathmatical model. For a ring, each step or change to a part is a step in the part history such as create a disk, dimension a disk, punch a hole in the center of the disk to make a ring, dimension the hole, etc. Without that history, the part can't be be edited, manipulated, or measured. It's that part history that makes the part measurable or changable in a CAD/CAM system.
The "smoke ring" is unmodifiable or measurable as there are no history steps, dimensions, etc associated with it.
Hope that helps