I have both. I love my Columbians, they are peaceful and have beautiful color. They shoal together well. I hope to always have some.
The Blue Tetras on the other hand, I'm not so sure about. In my community tank they are too aggressive. They are quite beautiful too though. They need to be in a group to keep their aggression to themselves, of so I hear. When I had my initial group in quarantine they killed each other. I lost one third in QT. I would like to try then again in a species-only tank.