Here's my take:
I assume you picked those pieces because you feel comfortable playing them infront of an audience and at a competition, and if you picked pieces that are harder than that, it would lead to a worse performance.
First of all, the pieces you picked are to me very technically and musically demanding. They are by no means easy pieces, and you certainly shouldn't feel embarrased!
Secondly, you wonder if someone is going to play Mephisto waltz or a Rachmaninoff sonata - I don't know the competition, but in almost any competition, it's true that not the hardest piece wins, but the most well-played. A good Chopin scherzo beats a mediocre Rachmaninoff anytime.
It would be much more embarrasing to pass up this big chance to perform some great pieces. I think your programme looks very interesting.
In fact, I wonder why everything has to be so technically difficult these days, I mean, we're talking about these pieces like they're Bach menuets. It's a Rach etude and Chopin scherzo. Great music, and best of luck in the competition!