when building up my wheels with phils i remember reading a bunch about how there is an issue with cogs that aren't Phil, EAI, or Dura Ace. Something to the extent that the other cogs weren't wide enough and it could result in stripping the threads (the surly's had a problem with this) - but that was over a year ago and i know surly had redesigned their cogs so maybe they will work fine now. i would email phil, but i also wouldn't put a cheap no name cog on a $230+ hub.