Savvy move, less “expensive” than standalone paid AA Club membership and could argue that SUB offsets the AF (at least 1st year).

Still gnaws at me. Too much credit utilization is a significant concern to (almost) every other credit analysis system. Too little is a concern seemingly only for Citi and perhaps only for this card from Citi. Seems counterproductive (for Citi).

Any other situations where too little utilization has adverse repercussions?