Funny enough, I have my Davidson in getting an English-threaded CK installed by my LBS. I made doubly-sure that it was an English-threaded unit, too, so that I could avoid any potential issues. The English-threaded Campy Chorus one never stopped loosening up on my rides after I changed it out from the old Super Record unit.

I know that English and Italian are interchangeable when it comes to headset and freewheel threading - it seems it's just the pitch of the thread that is a bit different. But considering the issues I've been having - and the cost of a CK - I personally would stick with English/English or Italian/Italian.

DD