Well since every Delta's bed area is identical, this question is for any Delta.
@Jim Beletti I noticed your Lippert is only 52.5# according to the page you linked. I don't know what the original weighs but if your struts can hold it, including bedding, that is a good data point for the stock strut capability. I have heard others say once they upgraded the mattress the struts must be replaced. I think there are 2 factors though: 1) the weight of the new mattress, and 2) whether it bends/creases a little bit or stays stiff and the struts bear 1/2 of the full weight. Does the Lippert one bend/crease at all?
I have only looked into this a little bit since my wife will ultimiately make the decision. I just look at the specs. The top rated one on e-trailer was I think 65#, and the Brooklyn/RVmattress one looks like between 100-120# depending on options. I think a queen from Purple was even heavier than Brooklyn. She'll probably end up with Brooklyn since so many RVer channels hype them up, and I'll be searching for struts.