Most of the grazing and animal behavior text books that I've read suggest that goats will eat brush and blackberries, while sheep will eat grass and broadleaf weeds. We've just placed a flock of 67 sheep and 13 goats on an Auburn property owned by the Placer Land Trust, and I'm pleased to report that our sheep can't read.
The Placer Land Trust hired us to control invasive plants and reduce fire danger on it's Canyonview Preserve in Auburn. The property is north of I-80 near the Canyonview subdivision and directly downslope from a professional building (see photos). The first paddock was about 1/2 acre of blackberries, thistles, dry grass and live oak. The flock polished off the vegetation in about 28 hours. The next paddock included poison oak and scotch broom, along with blackberries - again, they demolished the undesirable plants. Today (day 3), we moved them into more blackberries and dry grass (including a small burr, which the sheep love).
Our sheep obviously have not read the text books! They love all of the vegetation and are nearly as agressive with the brush as the goats are. The goats are more apt to climb, which means they will remove more of the higher vegetation, but we're really liking the combination of the two species.