Man, I just got my Shure E4c sleeves from Sensaphonics and I love 'em! They're custom made for my ears and fit great and make the E4cs sound better than before.
I also got a set of their Musician's Earplugs, too. They have replaceable filters for different attenuation. If any of you guys play in a band - these are great!
So far - they (the plugs and sleeves) are very comfortable and fairly easy to put in. The first time or two was wierd, but it's pretty natural after 5 or 6 times.
Sorry for the way way way way way way way off topic thread - but I've been waiting for these for a couple weeks and am very excited!
Sensaphonics.com for more info...or give me a shout and I'll give you my 2 cents