Keep in mind, there is not only a limitation on how much data the Sensor could push out, the electronics inside the camera need to also be able to process that in that time also.
So even if the Sensor was able to do more fps at full Resolution, the Bottleneck at that point would propably be the Image Processing / Memory, not the sensor itself.
I am by no means an Expert if it comes to Electronics, i am more of an Optics guy (so if i am wrong, please someone Correct my facts here, if i am wrong....) but as far as i know, the Chronos 1.4 Can Process 1.4 Gigapixels per Second Data Througput. Since the Sensor Resolution is around 1.3 Megapixels for a Full Readout, this amount of pixels could be Processed around 1000 times Per Second. So even if the Sensor would be able to do double the Framerate (wich i dont know, at what kind of Readout rates the Sensor itself would top out with more Powerfull Image Processing Unit behind it?), the Processing Unit / Electronics itself wouldnt be able to keep up with all the Data, and thats why even for really Short exposure Times (10 degree shutter or below) you will still be stuck at Max FPS for That Resolution, it wont change from exposure time.