Hello Lateral Line & lozzles,
In my opinion, you're both right.
On the one hand, it is true that many people shy away from barbs assuming that they are fin-nippers. This simply isn't true. Some, like gelius barbs and five-banded barbs are completely reliable, even a little on the shy side. However, there certainly are barbs that do behave in a way inappropriate to the community tank ideal.
Rosy barbs should be kept in a large group. I'd actually say at least 8 specimens -- a good idea with any schooling fish, whether barb, neon, or rainbowfish. With barbs especially, this seems to be the magic number of sorting out aggression.
Another thing: they're subtropical fish, not tropical fish. Seriously consider creating a tank around that fact. There are lots of subtropical fish that would make excellent companions. Corydoras barbatus, hillstream loaches, white-cheeked gobies, black-banded sunfish, green barbs, variatus platies, and paradise fish, to name just a few. I've been thinking about something like this myself. Lots of large cobblestones, some Egeria or Ceratophyllum planted in one corner, and a nice big filter with a spray bar to create a strong, even current. A wonderful mountain stream aquarium!
Cheers,
Neale