Hi cantsleep,
How much is your credit? Is it only for a mattress or is there anything else you could use it for? I certainly wouldn’t spend much if anything over the credit amount but you may be “stuck” with an unusable credit if you spend less.
That’s usually a good idea but some of them use only thin layers of lower quality foam (usually firmer mattresses) so if they have any like this then they may be worthwhile considering along with a topper (adding your own comfort layer). Some also use higher quality materials (often mixed in with lower quality materials) but these are usually in higher price ranges (an example is here and here). It really depends on the specifics but Jordans is one of the very few that lists the foam quality of their major brand mattresses (and as you can see most of them are low).
In addition to their two all latex models they carry two latex hybrid mattresses I would look at … the Taos and the Unison. Neither of these have any weak links (the quilting foam is only an inch and the polyfoam base layer is 1.8 lbs). You can read more about a latex/polyfoam hybrid vs an all latex mattress in post #2 here. Depending on the amount of your credit and whether your testing indicates either one is a good match for you in terms of PPP I would certainly consider them.
Phoenix