I heard about that. What we are talking about isn't perfrmance-it is that rumors ( from even very relible sources) that many problems accured on those engines.
From my expiince can tell you AAc set up is the best, but too many issues related to Al case and Al sleeve, so benefits from AAC performance are much smaller then issues following by that.
This is the reason why I don't make AAC for conventional design and this is the reason why my engine is AAC ( no sleeve, no cranckcase-one piece).
But again, I saw our engine on Airtronics and it was good ( i am not sure if it was AAC), but was good.