Buying ASIC miners goes against the common good. It give an individual the upper hand for a while until most miners upgrade to ASIC. By that time, a 5Ghps miner will give the same a amount of bitcoins as a 200Mhps GPU miner gave 6 month before.
In the long term, we all loose and the only winners are the ASIC manufacturers.
This is a fine example how group behavior eventually goes against the common good.
But I guess it's too late for that now... the hash rate snow ball is rolling faster and getting bigger by the minute.
It depends on what your personal goal is. If you want to be a big time miner and mine more than everyone else and rake in big profits then you need to pay the price by investing in that mining hardware no matter what it is at the time.
If you want to mine to contribute hash's to the network for the sake of Bitcoin then ASIC's are the way to go since they consume a fraction of the power of CPU/GPU's and create less waste heat and they can be had for a cheaper price than GPU's, unless, you want to be a big time miner, that is.
Hash rate is irrelevant, it really is.
So pick, your own personal good or the good of the network. I've made my choice. I could really care less about being the big dog on the network.
Attempting to be the big dog by trying to stop hardware improvements helps no one and, as you stated, is impossible at this point.
Sam