with me looking in IF anyone has ported the CGMiner HEX patch to BFGMiner ( and not finding it ) I've found your unanswered question.

Answer: the A2 is cheaper in the short term ( gets you started mining at at least 18GHash/sec, I've maxed at 22GHash/sec with out hardware modding it... yet.... cooling is an issue ).  If you have the cash/BTC definitly doubble the hashing power with the  most hashing you can get with what coin you can afford to invest in hardware and power cost per month.