While trying to keep my Model X under a 100k (after tax rebate), I had to choose between Leather Seats and Ultra High Fidelity Sound. After doing as much research as I could on the Model S forums and a few early comments on the Model X, I chose the UHFS. Given that I have to wait because I went with the 90D, I wonder if I should choose the leather instead and pay the $500 change fee? Anyone else in a similar position? What changes might you make while waiting for Model X to go into production?