Hi Turtlebed,
Both protect the latex to different degrees from oxidation (see the post I linked earlier here for good examples).
Both would generally provide “enough” protection for the latex. The different degrees of protection would just be one of the tradeoffs for each type of cover but in most cases either one would make a suitable choice and would be based on each person’s preferences.
In other words … I don’t think that the “protection” of the latex would be as significant a part of the choice between them as the differences in “feel” and temperature regulation between each type of cover.
Phoenix