Do we suppose the courts could handle the amount of additional work this would create for them? Nobody seems to have commented on the potential this has to create Japan-level judicial gridlock.
Courts deal with appeals all the time, not to mention from those who clog the courts with frivolous cases, which could in fact go down if the prisoners are given tighter sentences but set times to make their appeals.
I'm not going to discount your concerns because they are valid and it's difficult to compare our situation to that of Norway's, but I'd prefer we give this system a try. Don't forget that liberalized drug policies free up court time, as well, so I wouldn't worry too much.