Hi thatsdopefoo,
I have no personal experience with the mattress so I don’t know how firm it would feel for me and the perception of firmness and softness is also very relative to the person so it may feel firmer for some people than others depending on your body type, sleeping positions, and personal preferences and sensitivities. A conversation with the manufacturer will be a much better source of guidance about how the mattress may feel for you than anyone else (see mattress firmness/comfort levels in post #2 here).
The density of memory foam is the biggest factor in its durability but different memory foams that have the same density can have a wide range of firmness levels (see post #9 here). Again it’s always best to talk about your firmness choices and how well a mattress may match your specific needs and preferences in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) with a knowledgeable and experienced manufacturer who can talk you through your firmness choices and draw from the experiences and feedback of many of their customers that may be similar to you.
The guidelines I would suggest using are in post #4 here. 4 lb memory foam and 1.5 lb base foam would be inside the guidelines that would certainly be suitable for a lower budget mattress and for people that are in a more “average” weight range. As you probably know, I think very highly of Dreamfoam and I believe they compete well with the best in the industry in terms of their quality, value, and service so the mattress you are looking at would certainly be well worth considering if you are confident that it’s a good match for you in terms of PPP and you are limited to memory foam mattresses in this budget range.
Phoenix