Not an RJ pilot, but this is what I picked up on when working around them for 3 years.
CRJ-100/200 doors are closed on the ground. They can be opened via a switch in a panel located in the forward right nose section.
CRJ-700/900 nose wheel doors are open anytime that the gear is in the down position.
Personally, I think the CRJ200s would look a lot better if the doors were down all of the time. They just look weird otherwise.
They would also be a heck of a lot less dangerous.
The danger is that someone will accidentally flip the switch while you're looking in the gear well? Has anyone had that happen to them?
And as for the difference between the 200 and 700/900...I have no clue.
No the danger is that the switch could be put in the FLT/NORM position with the hydraulics OFF (while the doors are open), and when the hydraulics are turned on, the doors will immediately close...