If they taped out like it was claimed you'd be better waiting for the 20nm miner because it will probably exceed expected GH like the 28nm did.
It's a gamble, but there's probably a reason why they would swap you 28nm now for your 20nm future order.
For those who think ASIC hoarding by ASIC producers is killing mining you should campaign to have the Bitcoin algorithm altered to punish centralization!
It wouldn't be too hard to do, every 1% of the network an IP address has, delay new work by 1hr. Bitcoin should be decentralized!