Hi lauradanielle,
Shopping at a chain store would do that to almost anyone because the salespeople there know very little about their mattresses and what is inside them and almost everything they tell you is “marketing speak” or gobbledygook designed to sell you a mattress before you walk out the door. Most of the members here that have spent more than an hour or so on this site know more meaningful information about mattresses than the majority of salespeople in the industry that sell them.
I think you may be ruling them out for the wrong reasons. Latex layers inside a tight mattress cover don’t need to be glued (see post #15 here) and even the synthetic latex they use is a higher quality material than polyfoam (Note: Spindle is now only using 100% natural continuous pour Dunlop in their mattresses). Loose layers with a tight zip cover have the advantage that you can either rearrange or exchange them if you need to fine tune your mattress and also that down the road you can replace a single layer in the mattress if it becomes necessary for durability or comfort reasons without having to replace the entire mattress.
Of course I also think highly of Worleys and they have the advantage that you can test them in person which may also be an important part of your personal value equation.
I’m looking forward to finding out what you end up deciding and you are certainly looking at some good options.
Phoenix