I don't mean to say that the question is illegitimate (I also think about the differences between components and where they matter, where they don't), but that the question is ill-asked. The subject line says "LX or XT crankset?" The OP asks if people have experience with either crankset. There's a question in there somewhere, but the problem is that there's at least 17 possible questions in there, and the OP gave us no idea of his situation, what he's looking to build, what his concerns are, etc. He'll still get a fair bit of data from responses to his post, but it would be a lot easier for us to offer helpful answers if he'd put just an extra minute and slightly increased amounts of thought into his post.
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"c" is not a unit that measures tire width