Shure e3 and 34
I've been using Shure E3's and E4's since mid-summer. I recommend them strongly. The sound is very good. The E4's are a little better, but a little more money. Both are great at acting ss both earplugs and music transducers. I use the e4's with thw white extended plugs. Good compromise between fit, sound, and isoloation.
Once nice thing about the Shures is that they come with a failry wide variety of earplugs with different isolation damping strenghts. The more isoloation, the better the bass. But, you also lose more extraneous (read enviroonmental) noise. This is obviously desirable - to some extent. I choose to let some of the noise in for safety reasons on the bike. I also don't crank them up as loud as I might if I was just sitting around or walking. Again, to be safe, I want to hear some road noise.
All in all, they are a huge improvement over the Autocom speakers (with and without use of earplugs). I've read several articles on helmet noise - it turns out that over 60mph or so -ALL helmets are on the order of 104db of wind noise. That will damage hearing over time. So I was using the Autocom with ear plugs. Worked OK at best, but generally uncomfortable.
The Shure's give me the best of both worlds and are very very comfortable. I Mostly don't realize they are in. Net: if you can exercise a little restraint (don't play too loud, and don't over-isolate), isolation earplugs are the way to go.
BTW, haven't tried the Entomolycs - went with the Shure's because they seem to wired more ruggedly. The Enty wires look kindy fragile to me. A couple of people I've talked to who have tried both give them roughly equivalent sound quality.