The only recast voice actor I really have a beef with is Sue Ellen's. She sounds too nasal or something.
I agree, she sounds like a milder version of Muffy... and on top of that, Catherine sounds too young as well (since they were both voiced by the same voice actress); Catherine sounds more like a little kid and less like a teenager.
But yeah. This is why most cartoons shy away from real child voice actors and just have women do childish voices. You have to recast the heck out of them.
I just recently learned that the production staff actually has a regulation that all kid voice actors have to "retire" from ARTHUR once they reach the age of thirteen, no exceptions; but as I've said before, my main beef has been for years, they've been getting kids who sound far too young to voice Arthur... up after Mark Rendall and up till the start of 9 Story, Arthur has sounded more like D.W. and D.W. has sounded more like a raspy chipmunk; now for the current season, Arthur sounds like a girl, but D.W. actually sounds more like her original voice than she has in years.
That, take a look at this:
This is the guy who does the voice of Mr. Ratburn and Bionic Bunny... I don't know, I just can't imagine an animated yet resonate voice like Ratburn's coming from a face like that.