I beleive they use Toggle NAND, which is the best.
The Agility uses Asycronous NAND, which is the "worst." That's why OCZ Prices go Agility->Vertex->Vertex MaxIOPS (Asycronous->Sycronous->Toggle).
Only the Chronos deluxe uses toggle flash (which is also an asynchronous flash technology, but different than 'Asynchronous Flash'). The regular Chronos line and Callisto line use the technologically inferior Asynchronous flash