I am myself is a big IEM fan, but I'd attribute that to the constraints I face. Most of my listening time is while I am commuting, or when I am working in office. Both the times I can not wear headphones. Other times I don't have an air conditioner and I live in Mumbai, you should get idea. Wearing a headphone is a suffocating experience in this kind of weather. Otherwise whenever I got to try a good headphone I always loved it. I kind of envy the soundstage and thump a headphone is able to produce when compared with IEMs.
That said, I'll still buy ATH-M50x when I get transfer to Pune, for which I'm really trying : )
Good luck with that. I find earphones more convenient. Needless to say portable.