I wouldn't say it is "better" at moving water, but it does create a very nice flow when matched correctly to both filter and aquarium size. There are some definite hydrodynamics invloved in the design, and one of my favorite things about a Lily pipe is the ease with which you can aerate at nighttime. Surface film of any kind is a distant memory, for sure.
Regarding the CO2 dispersion question, I find that the positioning of the Lily Pipe on the side of the aquarium as opposed to the back and the placing the diffuser on the opposite end is a VERY effective way to thoroughly distribute the tiny bubbles produced by the ADA diffusers. I don't know if I could go so far as to say that the design has a specific relation to bubble distribution, though. It's all part of an overall system.
The P-6 17mm would be ideal for both your tank and filter size.