So potentially Burnin's boards will be hashing around 35% higher per chip? That is a massive difference and with the difficulty rise even a small difference counts.
Btw, great effort so far!
I think he only mentioned K1's couldn't hash that high. I imagine he will get similar hashrate out of the K16's as burnins.
The K1 is limited by power on a std USB port. Other than power supply there isn't any reason that the Avalon chips will hash slower on the K16/K1 than other boards. Noise has been an issue but with the new board revision I hope this is behind us. The K1/K16 designs don't clock lower or have some firmware limit that prevents them hashing as fast. The data rates outside the ASIC are quite low (2-3 MHz) and not a speed limiting factor up to short 420 MHz tests I did. But the revision 1 prototype board had no USB or PLL supply noise filtering and that was tested to be very significant in error rates.
The burnin numbers above show that water or air above 409 MHz isn't feasible, and that some clock rates have instabilities within the ASIC. Running at higher voltages may give you some few percent extra hashes but also puts more stress on the ASIC, and could lead to early failure over time. I'm pretty sure that the electron migration issues in GPU over-volting also apply yo ASICs, but I'm no expert in that area.