Hello, We have a long and poor record with mattresses and nothing seems to have worked for us since a long gone Sealy Posturepedic, but it would be much easier to list the ones that we've not found to work for us - so many now and such a waste of time and money. The latest is a Dunlopillo Millenium and we had high hopes for that because we'd used one of the original latex Dunlopillo mattresses years ago and liked it - the new version just isn't in any sense like the old one. My wife can't stay in bed too long without back pain and although the Dunlopillo is marginally better for me than some of the others we are now deeply frustrated and checking about the zip and link options is our last hope. One question is how much changing one side would be after an initial purchase. Another is how to try to assess what combination of half-mattresses to consider. My wife's main problems are with her back, but one bed gave us both similar problems and little comfortable sleep. If we go back to ground zero how do you suggest we proceed? I've not long bought a Dunlopillo split base so I would want to try to retain and use that, so we'd be talking about yet another mattress is we do go for this again. Thank you