Larry,
The reason I went with a handsfree unit was the simple fact that I despised having that thing in my ear. Yes, they are handy and easily transported from vehicle to vehicle, but I never liked the 'feel' of the thing in my ear.
Not to mention, road noise. We all know how much noise there is in the E - the only earbud I ever found that could work over most of the ambient noise (not counting the radio) was a motorola unit - but that still had the 'don't feel right in/on the ear' issue going. Between that and the fact that I would constantly have to turn the radio down or off just to be able to use the phone - it was just a royal pain in the arse. Then you still have the dial issue - the handsfree units can dial on voice command - totally hands free.
The handsfree units eliminate all that, they not only mute the radio but also use the radio's speakers. No, it's not portable - it's built into the sound system. But then it's not so apt to be stolen either.
I do a lot of traveling with the E, typically I do have to contact people while I'm driving - calling shelters, other transporters, rescues. The handsfree unit works for my needs, maybe it's not the best thing for everyone, but if one is looking for a good handsfree unit, the ones made by Parrot are just that.
Besides, I'm a big fan of having things work for me, not the other way around.