How hot did the heat sink get? Too hot to touch, or just warm?
Just warm, not too hot to touch. It's a small sensor, though - a 2/3" CCD with 1.4 MP, meaning a pixel pitch in the 6D/5DII range. But Zeiss uses some clever tricks to increase resolution. There are no microlenses, meaning the pixels have a 'sweet spot' - by translating the sensor in sub-pixel movements as a 2x2 or 3x3 array, a 6 MP or 13 MP image can be generated. There is a Bayer CFA in the color version of the camera, but full-pixel movements allow each pixel to be imaged through each CFA color. So, you can get anything from a fast-acquisition 1.4 MP color-interpolated image (actually, even faster if binning is used) to a longer-to-acquire 13 MP image with full color-channel resolution. Granted, that sort of thing only works with non-moving subjects - but fixed tissue tends not to move...
Yeah, it would be a little creepy if your tissue started...twitching!
Pretty small sensor, for sure. I guess a FF sensor and TEC would probably produce a fair bit more heat, but with heat pipes that heat could be distributed and released at various areas of the camera body. Personally, I'd love to see it happen. You wouldn't necessarily need to supercool. Twenty degrees of cooling would have a very substantial effect on dark current, which should help higher ISO settings.
I guess the only real drawback would be the power draw...I had to buy a separate specialized power supply capable of supplying a minimum of 13.8 volts to power the TECs I used on that old computer.