I'd like to be more specific about my original post, if I may...
RYR flies from DUB to ORK (Dublin to Cork), which is 144 NM according great circle mapper. EZY does very similar things with comaparable equipment.
According your theory this would be a perfect turboprop sector. Which, of course, it isn't, because of the volume.
Ergo it's not about turboprop or RJs, it's about passenger figures. In the USA, where sectors tend to be much longer, turboprops are used extensively also on longer routes.
Turboprop or small RJ: Most of the time this is not decided because of sector length but because of fleet availability. A company decides to buy eighter turboprops OR RJs, based on the average length of their sectors. When they have now a few sectors that are not so suitable, they wouldn't buy another aircraft type for this. Important is the overal cost, not the cost of the specific cost on this very sector.
Regarding BAe, I know this type very well, it might have problems from time to time (mainly the ball bearings, but not the gearbox), the passenger comfort is still way better than any turboprop. And my argument about easier handling in case of problems is also valid for her.
Dani