Lol I actually played "Un Sospiro" as my concert etude, and got 9/10. I REALLY enjoyed learning it, and most of it came pretty quickly. Some left hand stuff and the cadenzas are kinda tough to get clear - they didn't say anything about me f**king up the second cadenza, and they mostly gave suggestions for phrasing, voicing etc.
If you like that piece, it shouldn't be too bad; you can definitely play it with the stuff you have. I found the left hand near the end of the Bach Prelude in G major (which I also did for the exam) tougher than a lot of the left hand in the Liszt... you probably know which part of the prelude I'm talking about - IT's a nasty section that took more time than most of the tough parts in Un Sospiro.
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Suggestion Diabolique is a really cool piece. I wish I could play it... might be another suggestion for my prof

Shchedrin's "Basso Ostinato" is good too. I only heard of it recently, after it was added to the new syllabus. Looks very tough though.
Bartok has a lot of safe repertoire for a List E. My friend did one of the Roumanian Dances and got 14 or 14.5/15. The Allegro Barbaro is also good; it's very tonal too.
Muczynski "Desperate Measures" is AWESOME. Another I only recently heard. Go to the "Yamaha e-piano competition" website, and go to the 2008 archived videos. One kid (he's like 13) plays it as well as the Scriabin 5th sonata, and a bunch of other crazy stuff.
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For another Etude... I've played in the past few years the following from the ARCT:
Chopin: Op 10 #5, Op 10 #9
Liszt: Un Sospiro, Gnomenreigen
Rachmaninoff: Op 33 #7 (Eb major), Op 39 #6 (A minor), Op 39 #8 (D minor)
Gnomenreigen is a great piece, but might be overplayed for exams (as would be Un Sospiro).
The Chopin's are two of the easier ones which you could probably learn without any trouble.
I'd suggest the Eb major Rach Etude; a brilliant piece, underplayed, short and sweet. I played it at a recital 3 years ago.
The A minor I learned for a competition; the most difficult thing I've ever learned, and I wouldn't suggest it for an exam lol. It's awesome, and the first half goes well. It's a matter of keeping your stamina after an entire 30-40 minutes of repertoire, being able to hammer out all of those awkward, strange, tough-as-hell chords on the second last page. I spent so much time finding little ways to remember all of the inner notes to those damn chords. It sounds SO amazing on a grand piano though! The low A's booming in the intro, and again in the outro. I got good comments on this one, but the judge noticed my 'inaccurate' chords at some points haha.
The D minor is ok, but I found it about as tough as the A minor, because I can't play legato double notes without completely blurring the piece with pedal. That, and the "tempo piu vivo" on page 5 is ridiculous, plain and simple.
Pick something you enjoy playing; if you really like the Chopin Etude, keep it. One of my friends had 3 pieces in closely related minor keys (something like C minor, C# minor and G# minor), each about the same pace. That's probably worse than playing 2 by the same composer. Rach etudes are loads of fun; the most enjoyable pieces I'd have to say I learned, but they do take a lot of persistence [and large hands].