Well, a standard Q-ring changes between a 56 and 51, so it's still more than a compact chainring at every point. I can't find what the little ring is like, but I'd suspect it's the same.
Also while for some they appear to be working really well, it's not like a 5 tooth or 10+% power increase out of the nowhere.
You can mount a pair of 52/38. Maybe with a different cassette that would be enough.
The Ultegra 6750 has the 3D chainrings, which is nice, but I'm not sure I'd call it superior to 7800.
BTW, when going compact I'd always check if 50/36 isn't the better combo for a particular rider.
"Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.