Hi Jimbo770,
Your own experience will be a more accurate way to assess any changes you may need to make than any theory I can offer (I can’t feel what you feel on a mattress) but post #2 here and the posts it links to has more information about the more common “symptoms” and some of the underlying causes that may contribute to them.
I can also make a few general comments about each side of your mattress.
This would be “in the range” that was suitable for a side sleeper of 140 lbs but if there are some pressure points then slightly softer or thicker comfort or transition layers would certainly be worth trying. The N3 (medium) in the middle layer may be slightly on the firm side for her and she may be feeling some of its firmness through the 2" of N1 on top of it and if this was slightly softer it may work better or provide more pressure relief for her hips. I would have been tempted to try an N2 in the middle layer which would soften up the sleeping surface a little but I would be cautious about using 4" of N1 which is quite a big change with a thicker layer of very soft latex and would be a little more risky in terms of alignment … especially with back sleeping. The risk would be a little less because of her lower weight but it would still be on the soft side “in theory”. Since you have the additional layer on the way then it would of course be worth trying it in both of the combinations you suggested (an additional layer on top or to replace the N3 layer in the middle) because your actual experience may be different from any “theory” but I would be cautious with 4" of N1.
In your case the N1 top layer is probably softer than I would use in your weight range and I would tend to use N2 both for alignment reasons and for durability reasons. 100% natural Talalay is a little less durable than the blend in softer ILD’s (although it’s still a durable material compared to other types of foam in the same firmness range) and with your weight the N1 may not hold up as well as firmer Talalay over the longer term. At the very least I would tend to avoid any more N1 comfort layers other than the one you already have.
For your wife it would probably be OK (depending on her experience) but I would agree that it may be too soft for you. I would stick with the N4 or N5 as a support layer because a softer support layer may be fine for her but it could risk your alignment with your higher weight.
It’s probably more than you would “need” but it’s certainly not more than some people would prefer but again your experience will be more important than any theory. Again though … I wouldn’t tend to use the N1 layers with your weight and certainly no more than a single layer if you do. Adding more thickness will also add more softness with higher ILD’s which would be a more effective approach for a softer sleeping surface with your weight than using softer N1 IMO.
The goal of a mattress is PPP (Posture and alignment, Pressure relief, and Personal preferences) and I would prioritize them in that order. I would tend to make changes based on any actual symptoms you are experiencing rather than based only on subjective preferences which may lead to too many soft layers and put your alignment at risk.
Having said all this … your own sleeping experience is always more important than any theory.
Phoenix