so it would get better speed than the spartan6(wich is running at 50mhz if i m not wrong)
200mhz is the current figure (without manual placement).
beside that the clock speed is around 600/700mhz
It's unlikely the rep meant 600/700mhz for the hashing designs; he probably meant that the fabric itself can run at 600/700mhz. In other words, the registers and block ram will run at 700mhz, but any complex logic will run much slower. For reference, the Kintex 7 fabric runs around 500mhz, but that doesn't mean a CLB based miner would run at 500mhz (more like 300).
basically it would be possible to run 7 instances of the spartan equivalent instances in their chip
Looking at just the LUT count, I would agree with the rep, and I imagine they did the same (look at the LUT count). However, as Dexter770221 mentioned, performance could be much worse if their FPGAs are sparse in terms of carry chains.
At $3k per chip, I don't personally see a good performance/$ here. It just sounds a lot like a Virtex/Stratix chip.
