Fish keeping knowledge has evolved significantly since 2006, and our understanding of what works and what doesn't has changed. For instance, the majority of responses from back then suggest that keeping bettas with rummy nose tetras is acceptable, but we now know that bettas are best kept alone as they're not community fish.
Bettas can be quite particular about sharing their space and may not necessarily attack their tankmates, but they do release aggression hormones that can affect the other fish. And let's not forget that tetras have teeth, which can be a problem for fish with long, flowing fins.
While some people do keep bettas in community tanks, it's generally considered a high-risk approach. I've noticed that those who do keep them in community tanks often don't report back if things take a turn for the worse, like the betta suddenly becoming aggressive.
Given the age of this thread, I'm locking it to prevent further replies.