In ear monitors can be really comfy or very uncomfortable depending on how good your mold fits. If youre going to try them, first use a generic driver with a soft rubber bung, this will get you used to actually having something in your ears. Bear in mind that ipod addicts wear similar for hours on end... If you decide to take the plunge & stump up the cash, get your custom molds done at a recommended audiologist who knows about IEM's & not just hearing aids!!!! The mold needs to be an open jaw cast not closed, this means they will still fit if you sing along!! Get the best drivers you can afford - I use Shure E5's for angry dog rock and roll, or my UE10's for anything else. Bear in mind that a custom mold will give you around 20db of acoustic attenuation so not only do you get hifi quality monitoring, you also save your hearing for a couple more years ! ;-)