I very much like the idea of giving jurors specific roles.

I think telling people to hold off on proposing solutions would be very difficult to get to from current systems, for example the Knox case seemed to center entirely on the prosecution proposing a solution. If you stopped that, it would have a powerful but also partisan effect on cases where unlikely things did actually happen.

ETA: another good juror role might be someone to make sure they only consider legitimate evidence. (i.e. that was presented but not dismissed)