So far, the dynamic range in CIS devices is smaller than in CCDs. That is not good. For now, go with the CCD scanners if in doubt. Maybe someday soon, CIS devices will take over. Slide scanners are used by diehard photographers who still need to have their 35mm slides and negatives digitized for photographic editing.
Specialized scanners make the job much easier.
Since the source material is so small, these scanners must have a much greater resolution than flatbed scanners. Slide scanners have resolutions of about 2,700 dpi. Such resolutions allow 8 x10 prints to be created with little lost of quality. Professional quality can be obtained by scanners with an optical density of at least 3.2D for slides and 3.4D for negatives. Also demand the highest color depths for best results.