With a modern car, I strongly suggest keeping with an OEM designed seat. The Gen II airbag system with weight sensors and side airbags means the seat is now a critical safety item. A full racing seat, which for full disclosure I have in my Mustang and had in my first Focus, is designed to be used with a full roll cage, helmet, 5 or 6 point harness, and without an airbag. Putting a "race seat" into a street car can disable or alter the force of the airbag due to the weight sensing capabilities. It is also can pin the driver against the roof in a roll over. I have used both a composite (carbon/Kevlar) and a tubular FIA approved race seat on the street and have since decided that after countless bits of information from automotive engineers and my own observations on the function and design of the products, that using a racing seat on the street isn't the best in a modern car. I still run one in my Mustang and accept the risk since the car has a 6-point roll bar, 5-point belts secured to the roll bar, wasn't built with an airbag, and the car is rarely driven on the street. I would not consider installing a race seat in my Fiesta, even though I think they look fantastic and provide outstanding support.
As for not needing the Recaro, I can report that I did a back to back road trip with a regular Fiesta seat (in my 2011 and is the same seat as the base ST) and the ST Recaro and noticed a decrease in fatigue and discomfort in my knees and back with the Recaros. The Recaro seat provides additional support that decreases the need for the muscles to hold parts of your body in a position for an extended period of time. My right leg tended to want to relax against the shallow bolster of the regular seat, which meant I needed to use my leg muscles to counteract the tendency and keep the knee-ankle-and hip aligned with the gas pedal. After a few hours, this sucks. The Recaro kept my leg in the proper orientation and decreased discomfort and fatigue. A well bolstered and designed seat keeps the body in the optimal driving position and can transmit feedback from the car to the driver that can result in better driving.
