That's funny. I've been considering aftermarket seats as well. To answer your questions, yes, someone has done it, as suggested by Nader:
I'm interested in saving weight, getting a perfect fit, and improving my seat-of-the-pants feel of the car and track. I’d be interested to know what your research is turning up.
The seat you've posted above doesn't look much lighter than stock. What does it weigh?
The seat I posted is heavy. It wouldn't be much of a performance improvement over stock. It would not be my choice if I were looking for new seats. If you don't need a seat that reclines, there are lots of 12-14 pound seats available. I like the recline feature, myself.
The best seat I've found with a reclining mechanism is made by Cobra seats and is called the Misano.
http://www.cobraseats.com/
It's 24 pounds, with a carbon fiber/aluminum frame, and upholstered in leather and alcantara.
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At the end of the day, it's the mounting system that is the issue. You will end up having to get something custom fabricated, and you will lose your front/back adjustability.
I'm actually not that serious about changing out my factory seats. It's a lot of money for not a whole lot of weight reduction. It's on my list of things to do someday, when my wife stops being mad at me about all the $$$ I've spent on my engine. (Which will likely be a long long time.)
I would like to do something to brace the Northwind lowering kit brackets I'm using, however, as the seat has been very wiggly and sloppy since I installed the Northwind 1 inch lowering kit.