Nice, and many thanks for the release.
Now, some rough calculations.
At 80 MHps, I will need at least 3 of these to achieve a single 5830 hashrate.
That is $595.-x 3 = $1785.- at full price, vs. $190.- for the 5830.
Giving the 5830 is consuming $11.- a month in electricity, and assuming this board will consume zero electricity, it will take more than 145 months, or 12 years to recover the investment, always comparing to a 5830.
Is it really cost feasible ?
Your math assumes the difficult will be constant.
Eventually, the difficulty will reach a point where the power cost is a significant portion of the mining cost. Right now, power is about 10%-20% of the cost when doing GPU bitmining.
Let's assume that one year from now, power is 80% of the mining cost. At that point, FPGA mining would have a significant advantage over GPU mining even if the hash rates are same.