Hmm I guess I didn't describe it the way I invisioned it to be. I have no problems with the 1P2, it's just the switch to the customs that causes slight nausea. Well anyways, it isn't so bothersome. I just found it interesting, that's all. Lee might be right with the pressure idea. the 1P2 and Kaede are vented. Customs aren't. Perhaps that's causing minor disorientation.
Think of it this way, to anyone who's experienced motion sickness in the passenger seat before. When you close your eyes, it isn't as bad as it was before. Applying the same concept to IEMs, I was thinking that since a vented design might be more "natural" a switch to a closed/sealed design might cause some disorientation, which would get better over time as the brain adjusts to the new presentation.