Hi caw,
No … an innerspring is just one part of the materials and design or a mattress and one isn’t necessarily better than another. They can be very different from each other though and some are more costly than others so it really depends on the feel and performance of the mattress design as a whole and which one is the best “match” for you in terms of PPP. You can read more about different types of innersprings in this article and in post #10 here.
2.2 lb polyfoam is a high quality material and wouldn’t be a weak link in the mattress. The 1.8 lb polyfoam in the first mattress you mentioned is on the bottom end of the high quality polyfoam range and also wouldn’t be a weak link even though it’s a little lower density than the 2.2 lb polyfoam.
Phoenix