It isn't the jumps in the cassette that I am concerned about, just the big gap between the chainrings in a compact. 53/42 is a 126% jump while a 50/34 is 147%.

Top end is the least of my worries (). My current gearing is the triple I mentioned with a 10-speed 13x29 cassette and I rarely use the 13 so anything taller would be a waste.