Full frame is what I like, but it needs a telescope that can handle that image circle or a good camera lens.
I had to replace my 2.5 field flattener to a 3" field flattener.
You can follow my project here:
http://www.astrofriend.eu/astronomy/...flattener.html
Later when mirrorless full frame cameras come it will be much easier to fit the sensor distance to field flattener and also have filter wheel, off-axis adapter in between.
/Lars