this is interesting but I believe it is for the 1368 or 1366 chip correct?
the 1370 chip would do 1000 gh or maybe 1100 gh at your freq.
which is double the work. which would mean more rejects .
That's where the configuring of the asic comes in. The speed of the asic is not (meaningfully) related to the work the controller needs to do when the asic(s) are correctly configured. You can configure the asic to require few work updates and also produce only high difficulty (and thus rarely occurring) results. The only hard limit on the maximum #asics a controller can handle is the number of asic strings that can be connected to the controller and that depends on the number of serial ports the controller has.