You guys are correct, these will take a while to ROI, but you are also operating under the assumption that all of those companies will ship.  The only company in that list that has shipped a product is KNC, but their order page says they are shipping in Q2 or Q3, which means it could be between Apr and Oct, and since their other products have/are been later rather than sooner, my guess would be closer to Oct.  Of course they only made a SHA-256 ASIC, and a scrypt one is harder.  The other 2 companies you listed have not shipped products before.  IDK who that 3rd one even is?  So as far as shipping a working product, who knows when that will be.  Remember, no company as of yet has shipped an ASIC by their delivery date, just for reference.

There are also a few other companies to consider that you did not mention.  The Fibonacci project seems to be well underway with a scrypt ASIC, and BA says they have something in the works (although I would not trust or believe a word they say anymore)

Also the price for alt coins has dropped in he last few weeks.  If it starts to go back up, then positive ROI will be even sooner.  So there are many things to consider when choosing to buy these.  They also use very little power, which means they can run for a long time before not being profitable to run anymore.