Hi mer8735,
A mattress is only as good as the quality of the layers that are in it and without knowing the specific quality of all the layers in the Serta … there is no way to provide any meaningful thoughts about it. As you can see in the guidelines here … I would also avoid the major brands. While it may be better value than the iComfort (and also may not depending on the materials that are in it) … this is not a great comparison because neither of them are mattresses I would consider anyway. Sleep Innovations makes the gel memory foam that Serta uses in their mattresses (although there are different versions and qualities of the gel memory foam).
A forum search on “Dynasty” (you can just click this) and post #5 here in particular will bring up several posts with my thoughts about them including that what they are shipping is probably not the same as the foam densities that they list. I would suggest avoiding them as well and if you do decide to go in this direction I would call them “buyer beware”.
Post #12 here has a list of some of the better online memory foam options available that I’m aware of including several members of this site which I would personally feel much more comfortable dealing with, who have good quality and value, who disclose the quality of all the materials in their mattresses, and who meet the criteria I use for memory foam mattresses (listed in post #10 here).
Phoenix
PS: I saw you also posted the same question in another thread so I hope it’s OK that I deleted it and just left this one 