Went to the LBS. Told me changing the Chainring to a 50/34 would make a big difference, the only thing; I would lose my carbon crank. He changed it, I went for a drive, ALMOST NO DIFFERENCE. He scratched his head and said: I can change the cassette to a Mtn bike, but you'll lose your Ultegra derailer, but you'll have your carbon crank back. I couln't lose that , but after thinking about, I said DO IT!
What a difference. It's even better than my triple, but the bike is a bit heavier. I spent a total of 4 hrs waiting for him to do the chainring, put it back on and then cassette.