At the end of last week, I received P10 and CX4 and since then I'm taking photos with them and working on some comparisons. Here are some first crops.
First 28mm crops. All cameras were set to Standard settings and Spot AF.
As you can see, P10 appears to deliver sharpest photos and best corner performance at 28mm. Although the P10 lens construction (number of lenses, coating and positions) should be similar or the same as CX3/4 lens, it's evident that the lens assembly is different. In my opinion, it also explain why the P10 module is much thicker than CX body? This not only allows to start the P10 faster than CX (because of less time required to extend the lens) but it also noticeably improves the corner sharpness. At least at the wide end
I'm not quite sure about 300mm comparison. As you can see below, the P10 crops look a bit less sharp than CX4. I think it's caused by Spot AF where the P10 shot was slightly front focused. I will probably redo this comparison with all cameras set to Infinity.
Below you can check the colors (all cameras were set to Daylight WB) and overall exposure. P10 and CX4 are very close to reality. CX3 is surprisingly most overexposed at more or less the same shutter speed.
I will upload full resolution shots tomorrow.