I have two C-dale noise stories. One was the front hub. I am pretty convinced, though not absolutely certain, that it was vinyl-on-vinyl sound, like tight-fitting bearing seals. It would go away sometimes, or maybe if I shot some teflon spray in there. After many months I started ignoring it, and it went away. Same thing with the rear crank bearing. Since these were squeeky vinyl seal kinds of sounds I was not too concerned, convincing myself that it was only very negligible loss due to friction. I was confident they were not the actual bearings.
Regarding deraileurs- One thing about the 105 deraileurs that come stock is that the pulleys are journal bearings; i.e. friction fittings and not sealed bearings; i.e., with actual ball bearings. You can replace with Dura Ace pulleys for a nice upgrade.