Hi Davism,
I honestly do not think there is much comparison between the DreamCloud Luxe and the Titan Plus Elite when you start looking beyond surface comfort and marketing language. In terms of build quality, durability, foam density, and overall support design, the Titan Plus Elite is simply built to be a far more robust mattress, especially for someone at 270 pounds. The support system is stronger, the materials are generally more substantial, and it is designed with higher body weights in mind rather than trying to appeal to the broadest possible audience through soft showroom comfort. It does offer a cooler mattress profile with its microcoils in the comfort layer, and will offer a size sleeper a very nice body hug, which good support holding you up. Sitting edge support may not review the true meaning of edge support, which is when you are lying on the edge of the bed, that the Titan offers.
Of course, comfort itself is always subjective, and almost any company can make a mattress feel impressive during a quick 10 minute showroom test or the first few nights at home. The real question is how the mattress performs after months and years of use once the comfort materials begin to settle and your body is spending eight hours a night on it. That is where material quality, density and proper support become much more important than flashy marketing or luxury branding.
As for the DIY setup you mentioned with the QuadCoils, QuadMini layer, latex topper, and stretch cover, that route can absolutely produce an excellent mattress, but it also requires a willingness to experiment and fine tune. For some people that process is enjoyable because they like having complete control over the feel and construction. For others, especially during an already stressful period of life, it can become overwhelming and lead to constant second guessing. There is also no guarantee you will get the layering exactly right on the first try. If taking that route, you really want to work with someone like @DIYMattress, @Sleep_EZ or @Arizona_Premium to walk you though the steps so you get it right, combining some latex in the mix to increase the durability and structure of the complete set up.
Given everything you mentioned including your weight, side sleeping, sleep apnea, stress levels, and just wanting dependable sleep without creating new pain issues, I personally think there is value in keeping things simpler and focusing on a mattress specifically designed to support larger body types from the start. The Titan Plus Elite may not be the “sexiest” choice from a marketing standpoint, but from a practical standpoint it makes far more sense to me than the DreamCloud for your situation. You can always fine tune comfort later with a topper if needed, but it is much harder to fix a mattress that lacks proper support underneath.
Finally, I have to mention, support from a foundation. To be on the safe side, look for a foundation that the slats or less than 3" spaced, 2-3" wide and 3/4" thick, that offers NO flex and remains quite rigid. Something to look at that exemplifies this is the @MattressFoundations Terra foundation or Bunkie. They make a great foundation, and you want to use them as your benchmark.
Hope this helps put everything into perspective.
Maverick