When evaluating CBCT, I recommend downloading BlueSky Bio software because it is free and very feature rich. If guided implant surgery is one of your goals, you can use BlueSky Bio to design surgical guides . The BlueSky software has a great video tutorial library to guide you through basic functionality to the more advanced features, so, it is easy to learn as your needs evolve.
The next step is to request DICOM volumes from various manufacturers - both small and large volumes. Ask for volumes with restorations so you can see how the unit being evaluated performs when restorations are present. All CBCT units will produce artifacts such as scatter and beam hardening in the scan when restorations are present. This is why it is often necessary to use a scan appliance (basically an impression tray with radiopaque markers) and a dual scan technique to allow for the alignment of a scanned model and the patient's CBCT. When those two volumes are combined, a surgical guide can be planned and 3D printed.