I have Recaros in my '04 SVT Euro, and red/black SVT partial cloth seats in my '05 ST. In my experience the Recaro seat cushions are firmer than those of the partial cloth seats, thus one sits higher in the Recaros, at the same seat height as adjusted by the up/down switch. Mile30 is correct that the bolstering is firmer in the Recaros. There is a set for sale here, and on FJ by a member who feels too constrained by the Recaros, his FF name is Fattie, although I have met him, and I didn't consider him fat. Another benefit to the Recaros is that there is very little risk of staining the seat fabric, unlike the partial cloth seats which seem quite prone to staining, even from water. The partial cloth seats are not Recaros, they were made for Ford, I believe, by Lear Corporation in Southfield MI. The frames and tracks are very little different from the standard ST seats, although the frames feel to be of a higher grade and heavier gauge steel, the SVT foam and seat covers will fit the ST frames. The SVT front seat cushion frames each have a steel bar welded to the outside of the frame to better support the leather covered bolster, from people sliding over them when entering and exiting the vehicle The SVT foam also seems to be firmer than that in the ST seats. Over all, superior quality. I have no experience with the leather seats that were an option in the STs.
The SVT seats are much more comfortable and supportive, imo, than the standard cloth ST seats, which is why I drove to NJ from ME to buy mine from CaysE. They were, and still are, immaculate. They are coming out of my ST, because the car is being sold locally, and there are very few people locally who either know what they are, or will appreciate them. Perhaps someone here, or on FJ will appreciate them for what they are.