I think it depends on where and how fast you ride. At the 15-18 MPH speeds I ride on the flats I find that the 40 or 42 tooth middle ring keeps me in the closer spaced low end of the cassette. With a compact double I end up switching between the big and small rings with some frequency. In the mountains (or the big hills we have here in SW Wisconsin) a compact double with a 11-32 works just as well as the 12-25 or 12-27 with the granny gear on the triple. The downside of the triple is a slight increase in weight and Q factor. I like them both. My favorite is a compact chainset with a SRAM XX rear derailleur and 11-32 cassette- it will climb up even the steepest hills.