Hey richsass,
Welcome to the Mattress Forum! :).
Thanks for the post. I believe that a mattress protector is always a good idea to protect the mattress from stains and the normal moisture, body oils, and shedding skin that can lead to less hygienic conditions including the dust mite population in your mattress (not to mention protecting it from accidents). Mattress protectors are much easier to wash and keep clean than a mattress cover.
There are different types of protectors available depending on which of the tradeoffs are most important to you but the different types and their pros and cons and some sources for each are listed here in post 89.
Both the “waterproof” membrane type and the water-resistant wool type will protect against “accidents” from penetrating the protector (waterproof more effectively than water resistant) into the mattress below. Of course, where you buy the protector doesn’t matter as much as that you have one that is effective because many times the warranty doesn’t depend on which protector you buy … only that there are no stains on the mattress.
Thanks
Sensei