Considering they cannot use a 280% mount without the appropriate riding skill, only buying the 310% mounts would fall under the "advantage" category. Otherwise stuff like that is cosmetic and offers no advantage. Regardless of how small one may view that 30% increase, it is still greater than 280%. When you start drawing lines on how "how much of an advantage" is Pay-Win" then you fall into opinion territory, which is why any advantage should be considered "winning" in a sense.
Skipping content = saving time.