I was thinking the same... Tinfoil barbs get pretty darn big and are an absolute hand full of excitement. You could have them for a while but will eventually grow out of the tank size.
Severums are an awesome fish to put in with just about anything. Except for the same breed.... I have one with a tiny Synspilum and theres no issues. Had a few tiger barbs and the Sev didn't care about them, but my shark made short work of a few before I saved the rest...