The best features of RoadEng are it's ability to handle large amounts of survey data and the speed that you can take a concept to a finished design.
We tend to deal with large amounts of LiDAR data. Civil3D has implemented point clouds and they work OK but if you are building large surfaces we have noticed that C3D will actually thin your data and won't use all the points. Worse yet is that it doesn't tell you that it's doing this. With RoadEng always uses all the points. Sometimes if you have too many points it will crash but then you can go back and thin the data in areas that don't matter as much. You have full control.
We have tried doing corridors in C3D but they just take so much longer to set up and to finish a design. All of the volume and drawing out puts from RoadEng are pretty much fully automated. I can run a first draft of a 10km road over tricky terrain in one day with RoadEng complete with volume outputs and a full set of drawings. There's no way I could do that in any other program.
The only downside is that you can only manage one corridor per file. It would be great if you could even assign an additional profile that drives certain template parameters such as ditch depth. I have found ways to do this in RoadEng but it's a cumbersome process.
The other downfall is that the drawing outputs are sometimes a little too automated. You can't make small adjustments to the page layout of individual pages. Usually this isn't a problem but sometimes a little bit of additional flexibility would be nice.
I would recommend at least trying it. I received no formal training on the software because it is so easy and fast to use.
RoadEng's outputs (drawings, volumes) are all very automated which saves a huge amount of time. We find it to be significantly faster than using Civil3D to complete designs.