Difference between 'feel' and spring tension?

We are looking for a king-size pocket-spring mattress with all-natural upholstery fillings, and have been comparing the top four models of your Artisan range. However even after reading through quite a lot of the information on your very useful site, I am still not clear about how the two parameters 'feel' and spring tension relate to one another. All four mattresses are available in soft, medium and firm spring tensions so we can choose appropriately there: we are both in the 11-16 stone bracket so I assume you would normally recommend a medium tension for both of us. But as far as 'feel' is concerned, we find the following comments:Artisan Bespoke 004 - Medium Feel (no other special qualification)Artisan Luxury - Softer Feel ("Our softest 100% Natural mattress with incredibly deep sinking layers ...")Artisan Bespoke - Firmer Feel ("Our firmest 100% natural fibre mattress ..."")Artisan Bespoke 002 - Medium Feel ("... our highest specification highly responsive mattress")[The softer/medium/firmer descriptions of 'feel' do not seem to correlate in any obvious way with either spring count or GSM of fillings.]How do we judge from all this which mattress might suit us best? My partner likes a soft feel which would seem to point to the Artisan Luxury; I like a firmer feel which might call for the Artisan Bespoke. Or should we perhaps compromise on the Artisan Bespoke 002 which is described as medium in feel but "highly responsive" (and what exactly does "responsive" mean in the context of soft/medium/firm feel)? Obviously we could, if we chose to, have a different tension on the two halves of the mattress - although our body weights don't seem to indicate that as being necessary - but we can't do that with 'feel' so it's important to get it right.Your help would be very much appreciated!