A go-to portable IEM is very important to me. I've been looking for an IEM that I can grab over my customs when I need the isolation (quite frequently). I own the Monster Turbines(regular) + MDs. I've been looking to try out the COPPERS because I would prefer a more neutral sound than the MDs offer at the moment though they are very musical. I, especially, enjoy the supertips that the MDs come with and would prefer another set of my size.
At home, I have a stax setup (Weiss DAC202 -> Stax 717t II -> O2).
Portably, I have (HM-602/Itouch-64 -> Pico Slim -> FS Customs/Monster Turbines/MDs)
I prefer to listen to rock and pop.