it would not be the first time this (or several actually) of the etudes have been modified or adapted (heck even ones by other respected composers too).
it all depends on your reasons for doing so. generally i encourage your artistic sensibilities if you do it for musical reasons. that is we make technical decisions for expressive purposes, we don't make expressive /musical changes for purely technical ones (well some do, i was just never taught to ever do that).
also if you are just playing it for yourself, or as an exercise in arranging or transcribing, that's all good. but don't expect to have it considered a serious piece of music or art. just know your reasons and what the end product should be considered.
then again it's not like anything we say really matters. do what you like, enjoy it, if it works, cool, if not, cool too. heck a failed experiment is hardly an experiment as usually experiments are used to see if something is successful or not. so a failure is a success in that perspective (as you now accomplised the goal of knowing whether or not it works).
edit:
i think i just read the op original post wrong. at first i thought you were out to arrange or compose a piece of music just on the themem you like not just play the etude and leave part of it out. in that case, i don't think it's such a 'bueno' idea.