Clown barbs can hold their own with Tiger Barbs.
However, some points of interest on clown barbs:
1. Clown barbs get pretty big (4"-5" average)
2. They do tend to nip, though not like the tiger.
3. Like the tiger, clown barbs prefer to school and would probably nip less in a school.
How big is your tank? What other fish will you be putting in with them?