Security in bitcoin is a double edge sword by design. Asics are good for bitcoin if distributed in a mindful manner.
There is no double edged sword. ANYTHING presents a risk is hashing power is concentrated. There is nothing unique about ASICs. Litecoin for example is very vulnerable to Botnets. The limitations of LiteCoin make is highly likely that hashing power will never be decentralized enough to overcome that risk. LTC "bad" scrypt params are what made GPU mining even marginally competitive and for those bemoaning no "pure CPU coin" had LTC been made more memory hard (and thus non competitive on GPUs) it would have been even MORE vulnerable to Botnets.
Nobody built Bitcoin to be a "GPU coin" or "FPGA coin" or "ASIC coin". It was simply built to be efficient and secure on available hardware and overtime that openness lead to more and more efficient hardware. Today Bitcoin has the potential to secure the network with 17,000% higher efficiency than the first CPU miners. There is no possible scenario where that is a bad thing.
Security is only as good as its decentralization D&T.
So yes there is a double edge sword when it comes to bitcoin hash power in terms of security. The more concentrated it gets the more it hurts the network.
Who said securing the network was a bad thing? If that security comes from a centralized source then you have a problem.
You overlook the fact that ASICs as powerful as they are could harm the network should some wealthy investor decide to build an army of them and point them at the bitcoin network. Hence "double-edged sword". Don't be naive and think that people with deep pockets can't harm bitcoin if they chose to in terms of "securing" the network with hash power. Only an ignorant person would believe that could never happen.
Litecoin has yet to be bombarded by botnets. And dont think for a second that those botnets will bother to come mine litecoins when they are hardly worth a dime yet. As more hashpower comes online for litecoin, botnets will become irrelevant. Currently there is at least 12 TH/s of GPUs pointed at bitcoin. So there is quite a large amount of hash power in existence that may look for a new home if ASIC demand cant be met with supply fast enough.
BFL right now is just Unicorns and Rainbows. A select few (mostly avalon asic customers) will have a true edge over the rest as ASICs are released. Those who have GPUs will not be able to justify mining bitcoin if the diff for bitcoin skyrockets suddenly.
They are left with...
1. I can keep mining bitcoins at a loss.
2. I can sell my GPUs/other hardware and put in an order for ASICs (and get them someday).
3. Point my GPUs where I can convert what I mine to BTC.
(4). And once there is a payment processor for Litecoin that is linked to the banks, be sure people will start to spend litecoins as merchants remove the risk of market fluctuations in the price of litecoin.
Then things will be much different when it comes to the mentality of miners. They wont necessarily convert instantly to BTC.
