Since you like the JVC HAFXC51, you will probably love the JVC HAFXC80. The C80 has more detail than the C51.
So many people seem to push the $150 Yamaha microdriver IEM without even trying lower priced microdriver IEMs from other makers such as JVC, Meelectronics, or Fischer. The JVC microdriver IEMs do have very nice open treble and nice soundstage, however fit and comfort might be an issue if you don't find tips that fit you well. Since the driver is in the nozzle, those with a small ear canal might not find microdriver IEMs comfortable.