Hi griff_ka,
Post #89 here has more about the pros and cons of different types of mattress protectors including the thinner membrane type that you have and are considering and some comments and sources for some of them.
In general these types of protectors will have less effect on memory foam than the other types of protectors (depending to some degree on the fabric that is used to bond the membrane) but the membranes are also less breathable than other types of protectors so for some people they can sleep warmer (depending on the other variables that can also affect sleeping temperature that are discussed in post #2 here). The tendency for some people to sleep warmer would be common to all protectors that use a semi breathable membrane.
A forum search on malouf protector will also bring up a few more comments about it. For the most part they seem to work well for most people (but that’s also the case for other similar protectors).
Phoenix