While you wouldn't have PCM/analog inputs for surround, you could however use the HDMI inputs in back from your various components with HDMI output. PCM/analog surround inputs aren't needed per se. The receiver sends the appropriate signals to the various surround speakers in your HT. The blu ray player (etc.) sends the audio the receiver where it is decoded. No issues there unless I missed something you require. [ What other components will you be using in your HT? ] edit: i just looked again- the 607 appears to offer 7.2 channel sound.
It sounds like the benefit is the built in iPod dock vs the Onkyo dock that is an accessory. You wont' be gaining much from the THX certification IMHO. If you are familiar and comfortable with the Onkyo performance and can live w/o the iPod dock, it may be the better value. OTOH, one of my favorite gifts from my wife was the Onkyo dock she surprised me with (I have an older model, btw).