Well, like I already said, the Bombardier Montreal offered 604 to CRJ conversion which was about 7-8 days long.
Some class room studies focusing on differences, then 2 or 3 sim sessions and a check. And of course the closed book written, it being a JAA course.
That was at the end of 2007 and I did it in Montreal.
Again, like I said already, to my knowledge, that is not offered anymore.
And the 604 and CRJ (850) are very close to each other indeed.
No VNAV selection on FCP on 850, but that is the main difference operating wise.