Not to be a damper, but I think barberi will get too big for a 16G. They're part of the tomato (A. frenatus) complex, which average about 4"-5.5" fully grown. Personality-wise, I would imagine they're similar to other members of that complex--territorial and aggressive.
Another thing to consider is the fact that--at least in my experience--female tomato-complex clowns are hard on their mates. The pairing process can be rough. My cinnamons fought violently before settling into their respective roles, even though they were still so young when I got them that they still had the remnants of their juvenile center stripe. They've calmed down a lot and get along well now that they've bonded. Even so, my female still pushes the male around and kicks him out of their anemones during the day. A bigger tank gives the subordinate fish more room to get away from the aggressor.