OK, between foolio acting the fool and Sky Render completely speaking out his arse, the misrepresentation of Kirkey needs to come to an end. Some folks here are actually looking at this thread with interest, and we should at least
try to make informed comments (or better, stay silent).
The aluminum seat pictured earlier (in bare form) in this thread isn't a Kirkey, it's an Ultrashield. They're a reputable manufacturer and make a solid/safe seat, but frankly having been in both I think the Kirkey are better made and more comfortable. I've never heard any racer bash either seat manufacturer.
Aluminum seats in general have proven their worth time and time again in 200+ mph crashes (is that what you had in mind by "triple-digit speeds"?). Kirkey has been manufacturing the very seats that were in those crashes for over 25 years.
Now you come to your FIA certification. First, read it. What you'll find is that composite seats lose their certification after 5 years (much like composite helmets, they degrade over time and exposure to elements). I know some organizations allow you to continue to use them after 5 years, but then you are required to support the back.
Now you come to the ease of manufacturing - composite wins hands down, as it doesn't take an experienced hand to lay down glass over a buck and make it look decent enough to sell. (Doing it right is another story, which is why you pay the price for a quality composite seat.) The reality is that this has spawned a slew of fake seats from over-seas (some with convincing FIA stickers). So you had better be sure your vendor is well-known.
As for safety, unless I was required by competition rules to run an FIA seat, I'd go with a Kirkey every time. I've seen video of composite seats flexing side-to-side, and even without a back brace the Kirkeys are nowhere near as flexible. Personally, I'd recommend to anyone to run a bolted-in back brace, as it is stiffer and safer (ties the seat into the chassis & roll bar/cage at an additional point). You can't easily do this with most composite seats, as it compromises their integrity.
For those still reading, here are some pics of the Kirkey Deluxe Road Race Seat structure:
Best,
-j