Steve, I don't know that article but the reasons given for a flat thermarest only are pure b.s.,,removing point pressure from the specific area that is the cause of the pain will be done much more efficiently by distributing the pressure over a larger area,,the best way to so that is with a deep carved seat where the sides/back of the seat have depth to support the fat/muscle of your butt, increasing support under the thighs can help but it's not as significant as whats happening 3" away from your sit bones and sciatic nerve. Removing point pressure with a carved seat will allow for circulation more effectively than sitting on a 1" air/foam mattress.
I've made a hard fiberglass seat that is more comfortable than a thermarest sitting on the bottom of a kayak, the significant aspect of the support is that the hip braces are contiguous with the seat. The sport seat is great for fine tuning a seat or paddling first aid, but it's like wearing gloves, something else should change first.