Do I need to use a mattress protector?

Mattress protectors are great for protecting the mattress (from stains, dirt etc) and there are also claims that using one protects the health of the sleeper, as you're able to keep dust mites at bay, which is especially helpful if you experience bad allergies.  

In terms of breathability and heat regulation, there will be some difference to the effect of the heat regulation of gel memory foam layer. The degree of difference depends on the kind of material of the mattress protector, i.e., synthetic materials will trap the heat more than cotton or wool varieties.