I agree with Giovanni that the earlier Casavants tended to be very nice. There is a fabulous one in Montreal at the church of St. John the Baptist. I was always a great admirer of Bernard Lagace, an organist from Montreal, and I had a few lessons with him years ago (in Montreal.) His wife recorded at St. John the Baptist years ago and the record was gorgeous! I heard the organ in person, but not demonstrated well.
I also agree that many Casavants in the "NEO" Baroque style were not too attractive. However, organs that scream like that are not even close to what a real German Baroque organ sounds like. That being said, I learned early organ technique on a Casavant tracker in Scranton, Pennsylvania. This one was designed by Brunzema, and it is a very successful and beautiful example in German Baroque style. It does not scream at all and is quite beautiful in character. But I would say that except for a few instruments like this, organs in Baroque style were not Casavant's forte. I have played one large Casavant in a more modern ecclectic style which I liked. I also might tell you that I worked for a few years with someone who at one time voiced organs for Casavant, and now works for Fisk, so I have seen a number of Casavants in the Philadelphia, New Jersey, New York areas. There's a gorgeous Casavant in Queens, NY designed and voiced in French Romantic style--not a very large instrument, but very nicely voiced.