I think the easiest answer would be, if you truly enjoyed the E3s and had no complaints whatsoever, buy another pair and be happy. At the very least you know you're getting something you'll be satisfied with.
The tougher answer I cannot give you as I don't know what your preferences are, but if you're looking for portable/commuting gear I would stay with IEMs. I have tried many of the smaller portables (KSCs and PXs come to mind) but find myself coming back to IEMs again and again because they are so darn versatile (both with music genres, and in the sense that they seem to be able to relax you on the car, the train, the plane, the boat, or whatever mode of transportation that happens to suit your fancy). I'm fairly sure that more than one person here at Head-Fi has found their commute an entirely different experience with a good portable setup.
Hope this post at least gives you a general direction =)