Trust Crutchfield MOST of the time! I found out first hand that their fitment data is around 95%+ accurate. Well let me rephrase that slightly. When they say it fits they mean that its completely plug and play... with no modifications.
The reason I say this is because I had purchased two sets of Infinity Kappa 682.7cf 6x8's for my old 05. The Kappa's fit like a glove in the rear deck but required a slight bit of "gentle persuasion" to fit in the front. Basically all I needed to do was round out a hole on the speaker mounting bracket a tad and find a safe place to mount the external cross-over. These mod's took me 3 - 5 minutes tops to complete. According to Crutchfield, however, these Kappa's would not fit in my car.
One thing I miss about the 05 is the process to replace the rear deck speakers. In the 05 I removed the speaker covers and then used a ratcheting offset screwdriver to remove the mounting screws. In the 08, however, this basically requires a lot more effort.