Hi dunbroke,
The first thing I would probably suggest is to give things some time before deciding on a topper. With some of the “non mattress” issues that you are facing and the normal adjustment time of a new sleeping surface … it would be very easy to make an adjustment now that didn’t turn out to be as suitable in a few weeks.
The second thing that may help with the shoulder issues is a pillow. While you don’t mention height/weight/sleeping positions … a new mattress can affect whether the old pillow you were using is still appropriate and keeps you in alignment. A pillow is a significant part of the overall sleeping system and can particularly affect upper body issues.
Finally … I would tend to avoid memory foam as a choice for any younger child. The product you mention is from China and manufactured by Zinus (the green tea is the giveaway about who makes it) and while they are CertiPur certified … I personally don’t think that memory foam is a good idea at all for children until they have finished growing both because of spinal alignment and development issues and because they don’t yet have as developed an immune system as an adult. Slow response materials are just not a great idea for children IMO.
The seven comforts topper is a great product and I would think of it more as fine tuning that can provide localized pressure point relief as opposed to a “non shredded” foam topper that would provide more of a softer surface across the whole mattress and distribute pressure over a larger area of the body. Which would be “best” would depend on the specific “symptoms” you were trying to “correct”, the “degree” of pressure relief you were trying to achieve, and the overall “feel” that you liked the best.
Edit: see post #52 here first if you are considering ordering this topper.
I think it would make a good choice for your son but for you I would first wait a bit and then try to get a more accurate sense of whether you were looking more for an overall softer “feel” (which may indicate a low ILD foam topper which would be similar to what many people are used to having in the top of their mattress) and a thicker effective comfort layer or for more localized relief with a slightly firmer “feel” but which would relieve the “symptoms” that were causing issues once the initial adjustment period was done. Bear in mind as well that all of this is very subjective and based on different people’s perceptions, on the mattress that it was being added to, and on the wide variety of different body types, sleeping styles, and sensitivities of different people.
Phoenix