Mining profitability sounds too good, where is the catch?
Keep in mind that difficulty also evolves over time: the more hashes the network produces, the higher the difficulty becomes.  As of this writing the difficulty is 148,819,199.  By my computation, each additional 275GH/s rig that joins the network will increase the difficulty by about 40,000; if 4,000 of them are sold, the difficulty will more than double (not counting all the competing mining rigs that may join the network).  And of course, in a few more months, there may be even more powerful rigs available.  So you should expect difficulty to rise, perhaps sharply, and this will decrease your profitability over time.