My commute is only 8 miles round-trip, so a little different. I use the rain cape if it's a steady rain with little wind. If it's windy, the cape is pretty worthless; I'll be wet from the bellybutton down.
OTOH if I'm going out for 40 miles in the rain, I'll wear a rain jacket and rainlegs chaps. I find the cape just too fussy for that length. Even with pit zips open, I'm going to be sweaty inside the jacket; that's how it goes.