The CRJ doesn't have a two piece door so wear issues aren't really a problem. Also, the latest version of the door is a well-damped device that has had no in-service problems to speak of. Flap issues likewise have been worked through from their earlier annoying failures. The nose down approach attitude which made for a pretty flat flare on the 200 has been corrected by the addition of slats on the 700 which now flies more like the big boys. Overall, nice performers that make money for the operators. Send me a direct message if your questions get deeper in the technical aspects.