Hi TimJohnst,
Memory foam and latex are very different materials but both can do a good job with pressure relief so the choice between them is really a personal preference (see post #2 here for more about the difference between them).
Memory foam will change some of the “feel” and properties of sleeping on latex (such as ventilation and temperature regulation and the resilience and ease of movement of latex) which is likely why you chose latex in the first place so I would tend to stick with the materials you prefer unless you you are confident that you would prefer sleeping on a memory foam topper.
There is more a about choosing a topper in post #2 here and the topper guidelines it links to but when you can’t test a mattress/topper combination in person then a more detailed conversation on the phone with a knowledgeable and experienced manufacturer is usually the most effective approach … particularly if they have a good exchange or return policy so you can use your actual experience to decide on whether your mattress/topper combination are working the way you want them to.
Phoenix