Hi incognito,
A softer latex topper would certainly be softer and more pressure relieving than a cotton mattress pad and as you mentioned the cotton will also be subject to compression and an increase in firmness over time.
I would also be very cautious about using other people’s experiences or reviews on a topper (either positive or negative) as a reliable source of information or guidance about how suitable or how durable a topper may be for you and in many cases they can be more misleading than helpful because a topper that would be a perfect choice for one person (or on the mattress they are sleeping on) may be completely unsuitable for someone else to sleep on (or on your mattress) either in terms of comfort, suitability, or durability (see post #13 here).
I would pay much more attention to making sure you are getting accurate information about the topper you are considering so that you are making an informed choice and that you are comfortable with the return/exchange policy as well just in case the topper you choose doesn’t turn out as well as you hoped for.
I would consider SleepOnLatex to be a knowledgeable and reliable supplier and they will provide you with accurate information about the toppers they sell and they are one of the online suppliers that are listed in the component/topper list here. They would certainly be worth considering if you are looking for a 100% natural Dunlop latex topper although I noticed on their site that their toppers are on back order until June 18th.
There is also more information about choosing a topper in post #2 here and the topper guidelines it links that can help you use your sleeping experience as a reference point and guideline for choosing the type, thickness, and firmness for a topper that has the least possible risk and the best chance for success.
Phoenix