That's a great idea, and very well executed.
One thing I can say, and others may have more knowledge on the subject - I dont believe it is legal to modify the seat/safety components of the vehicle. Again it may depend on your state, and insurance provider.
Even though you have better materials than the stock ones. If there was an accident and the seat let go (for whatever reason, unlikely as it is) it may become an issue or point of contention.
I know typically insurance companies ask about modifications. I'd just be weary on this one.