I would take it that Claymore is having difficulty getting to the current performance of Optiminer v1.6, and he doesn't want to release an update until he achieves that. Folks that are waiting around for Claymore to measurably exceed Opti v1.6 are dreaming. Miner optimization doesn't just go on achieving improvements forever; at some point you've gotten as much as you're going to get. I think that point has arrived, for the most part.