Hi HotTubMan,
1.Yes CD ozonators have a higher output (usually combined with a larger/longer contact chamber) which is said to be a more effective oxidizer.
2. Although there is no UV light to replace in a C.D. ozonator, you will need to replace a "chip" in about 2 years (approx.$50).
3. Lower output may be beneficial to pillows and covers, but a properly designed and engineered C.D. ozone sytem will provide higher output while not damaging pillows and covers due to size of contact chamber.
The main purpose of an ozonator is to help keep the spa water clean and healthy.