My roommate took one of the CRJ/Jet transition courses in college...he said the major benefit was learning to operate in a crew environment vs. the single pilot environment we all started with. It also helped with systems.

The thing with airline training and procedures is, though many airlines may fly the same airplane, they all may have different procedures/flows/callouts/etc...that you will still need to learn. Even with a CRJ course, airline training is still a major untertaking that needs a LOT of study.