Thanks to some kind person here, I've been working on this WikiDevi page about the 801.11ac 'radio chipsets'.
Starting about a third-the-way down this long LONG page, there is alpha-chart of AC devices.
ASUS 87U is using a Broadcom BCM4709A0 chipset then a mix of Quantenna & Broadcoms. The Linksys WRT1900ac router is using Marvell chips thru-out.
In Bill's above post, his SMALL NET BUILDER strikes the odd blow for a little guy by showing the $100 TP-Link 1750ac with a thru-put that's a 'mere' 25% less but $150 (and 150%) cheaper than the LinkSys WRT1900. To me, that's the definition of "value".
And don't forget that the adapter to reach these max performances is the $100 Asus, by the way. Not much competition out there in the adapter field at this point.
This incredibly slow appearance of adapters following all of these leaps in Routers is strange. It makes Bill's cautions about Wave2 technology sound like a wise consideration - when the industry is only jumping ahead in routers, then dragging their feet on the other needed half - why?