hi, i am no expert AT ALL but i do have barbs ( naughty little beasts and i love them)
I started with 5 cherry b's and 6 minnows. Then added checkered barb's. I would say from my experience and from advice given to me that you should definately get a school of the same type. Mine now mix as a school when the mood fits but they do stick to their own kind MOST of the time.
I have to say that i never hear much about Checkered barbs but they are lovely, calmer than the Cherry b's and the male has lovely orange fins with his Check body. I'll try to get a pic of them to post.