The specific difference between the Cinestill 2-bath developer kit and the Tetenal 3-bath developer kit is that Cinestill leaves out the final stabilizer bath, or more precisely label it as 'optional'. They claim in their data sheet that modern C41 films contain embedded stabilizer chemicals, which are released during the first two baths, so that a separate final stabilizer bath is not necessary. Since the stabilizer bath is fast and easy to use, I am not sure if I personally would risk leaving it out.

Using or leaving out the stabilizer bath will not have any impact on the image quality, but may have impact on the archival properties of the resulting negatives. A typical stabilizer bath consists of an antifungal and a hardening agent. Since the emulsion is made of gelatine, it can be prone to fungal growth when stored, which is prevented by the first agent. The hardening agent makes the emulsion less prone to mechanical damage like e.g. scratching.

For home use, the number of baths in the original C-41 process has been reduced by combining multiple steps into one bath. I doubt that this has any, or significant impact on the image quality or archival properties of the negatives. It does however have impact on the durability of the chemicals. The working solution for most C-41 home use kits only keep a few weeks, while separate baths for large scale lab-development keep much longer and also have the ability to be replenished by replacing a small part of the working solution with fresh developer from time to time.

I have used Tetenal's 3-bath C-41 kit quite a lot and also made traditional wet-prints on paper from the negatives. I doubt that the results are in any way inferior to full-scale, 'many-baths' C-41 development. I would expect the Cinestill kit to be just as good.