The original Curt hitch for the EX had some problems but they've had a new one out since the end of Jan 2009 that addresses all the issues. If you contact them, I'm led to understand that they'll swap you out and even reimburse your labour costs.

Here's a link to the new Curt hitch at an online site:
2008!Infiniti!EX35 Journey!Draw-Tite, Reese, Hidden Hitch, Valley and Curt search with the!Hitch Hunter ™ by etrailer.com (800) 298-8924

FWIW, a member on another forum reported that he used the Curt 11510 hitch with a Thule 970 Helium bike rack with great success. (I'd post a link but I'm pretty sure that would be against the rules.)

HTH