Blues grow as quickly as channels but ultimately reach much larger sizes; in the wild it takes them 9-10 years to reach 3 feet in length, but they may grow much faster in a warm tank or indoor pond with a constant food supply. They continue growing after that, and can reach more than 5 feet long and well over 100 lbs.
I have not kept them myself and cannot comment on their personalities. Many public and commercial aquaria keep them; I know several Bass Pro Shops have blues, and so does the Tennessee Aquarium. If you are seriously thinking about keeping this fish, you should contact one of them.
Moontanman- I think number 4 is the white catfish (Ameiurus catus); the record is 17 lbs. I assume you're talking strictly freshwater cats; otherwise I think number 4 might be the gafftopsail cat (Bagrus marinus).
I'm a bit confused on the pet trade Ictalurus. Most of the "blue channel cats" I see are clearly normal channels; I assume the "blue" name is just to separate them from the albinos. But other people say they see fish that appear to be hybrids in the petstores.