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Either you're lying about your repertoire or you're being way too overly cautious. This is leagues below La Campanella. Weird rhythms or not, with what you currently have under your belt you shouldn't have too much trouble learning this. Your typical Chopin nocturne pretty much demands similar things [delicate tone, fast and light passage work, and good cantabile playing]. I'll pick op. 27 no. 2 since I just finished polishing it, the nocturne's a bit harder for obvious reasons like length and amount of content.