UPDATE #1 ... first, thank you for the feedback. I appreciate it!

So... I've swapped out the 6600 for the new 6800 crankset, and as previously stated, I started with the stock Ultegra 6800 52-36 unit and swapped out the 36T for a stock Shimano 6800 39T inner ring. Without any adjustments to the FD, I was unable to get the chain to sift from 36T to 52T ring... to isolate the potential issue, I re-installed the 36 (should have done this first of course) and retested the shifting from 36T to 52T. In the 52-36T configuration, I managed to complete the shift, but it was horrible and took a good deal of effort to complete (not what I'd classify as a success). After reinstalling the configuration to 52-39T, I removed any excess cable slack, and adjusted the FD high limit set screw with a 2/3 counter clockwise turn and retested. Resetting the FD and adjusting the high limit screw was all it needed... the shift from 39T to 52T was successful.

This was stand only testing, so I will still need to perform a ride test to get a practical assessment... so far, so good...