Well, so i arrived at the aircraft today and the maintenance staff told me everything is ok, absolutely flyable. Of course, the lower DU was INOP, and the right RA was inop too, which meant the autopilot would disconnect at GS intercept...
Good thing two of us were there and could normally operate the aircraft without any problem, computers alone probably would have encountered a couple problems.
By the way, it is possible to fly manual CAT III approaches and landings, more than enough CRJs and others around that do it quite often.