I auditioned both. I had to A/B for about 30 minutes before I heard a slightly fuller sound with the 370. If you can't hear the $90, no it's not worth it. But give both a good long audition. I took Hell Freezes Over on DVD for the audition. I had the store run the DVD in 5.1 and turn off all the other channels but the center, so all that I heard was vocals with no music. That's where I really noticed the difference, but again, it was very subtle
I sold my CC-170 and got the CC-370 2 weeks ago and it was a major impovement. I was not even considering the CC-270 at all. In your case, the $90 is worth it if you plan to upgrade any of your front/surround in the future.