Okay, I checked out the site for the thin line - they are quite different :)
Sorry, I also forgot to mention the supracor pads are quite expensive - but last forever and in my opinion are well worth it.
I use a western, and the girl who leases my gelding bought a cute little english one last year. We never see uneven sweat spots or sore spots (even after 25 mile competitive trail rides) - and sweat under the saddle is actually minimal because of how it allows air to circulate.
I actually can't believe I have not seen this pad for sale in catalogues anywhere.