I have been experimenting for about three weeks with much lower cadences on a slightly harder gear and within two weeks I noticed that my HR between low and high cadence has not changed much at all (40 mile commute four days a week and the times overall are almost the same too). BUT, it does require a little bit of time to get adjusted to the higher torque/low cadence stuff (just don't go too low and too high of a gear or else you'll knees will have a word with you later, lol). In the end yeah, switch it up. Nothing wrong with a little bit of everything. Keep the body guessing, lol.