I have the same setup and I don't really think anything less would be useful for me... I've never even used that combo. For me the key is maintaining momentum into the hills and then giving a little more effort (Or a lot, depending on the hill) to keep from slowing down too much.
Time your shifts well. (I still stink at this)
If you downshift too early of the flats, you'll lose momentum.
If you downshift too late, you'll either goof something up because you're putting a lot of effort into turning the pedals at all, or you'll just stop, and from then on you're stuck walking.