I've heard them both, but on different occasions with plenty of time elapsed in between. I remember being very impressed with the C1s, while the Ushers seemed just ok. You might want to check out the 'Storm of a Difference' portion of this review of the Ushers. It has a nice comparison of those to the Dynaudios. Good luck with whatever you decide!
http://www.stereophile.com/standloudspeakers/508ush/index.html
http://www.stereophile.com/standloudspeakers/508ush/index.html