My ears canals are very very narrow. The CK10 is uncomfortable for me. I've had them since 2008, so I am probably the most CK10-experienced headfier. I didn't start this thread, but I have the unique privilege of tipping of our OP and a number of people back in the day. I am proud of my accomplishments, and I love this earphone. But... it never has been comfortable for me.
That's a shame about the comfort. I bought mine in 2010, based on your review and have been very satisfied. I have large ear canals and they just disappear inside - can barely tell that they are there.