We have a hopper which is very much like #1 but to fix the jamming problem we found that If we off-set where the two angles become strait by a few inches the jams are reduced to next to nothing. Our simple solution was to just put across a 1" diameter plastic rod across one of the edges, but If you are designing a new hopper you could make something better integrated into the design.
If you look closely you can see it here:
http://www.chiefdelphi.com/media/photos/23277