My Cannondale synapse HiMod BB area started creaking after 2 years. I estimate about 8k klm during that period since I was using the bike only for races and brevets and not for training.
After using the procedure mentioned in my post above the creaking was eliminated and returned after 2 yrs, and again I used the same procedure; 5 years later (a month ago) it returned. Using the same procedure the creaking disappeared.
Both BB brgs turn smoothly to the feel with the DS very slightly less.
I have never found the chain ring bolts loose.
Since the creaking goes away with this simple procedure I don't plan to change anything.
I understand if I was to replace the crank with a Shimano I would have to install a sleeve in the BB, and have read that this setup can creak also.