I have no qualms recommending the Netgear R6300 ... A very good AC wireless Router.
Certification means that at a very basic level interoperability is assured ... However there are varying options and not everyone producing chips for This new standard will support all the options ... So at a higher level interoperability is not assured for the more advanced options some may choose to offer.
If you are nervouse about being an early adopter then stick with N. IMO certification for the AC standard will not happen until late 2013