Hi I've partially switched to corona render recently and I have to say that I love it, unfortunatelly there are still some feature missing so here is a list of improvements that would make it better in my opinion.
Unfortunatelly in my opinion the native C4d fresnel shader is very restrictive, i think having the option to directly insert textures into the 2 nodes and mainly having the chance to manipulate the mixing curves through the graph rather than the color slider would be much more better.
Corona color correct is good, but could be better if it could integrate the edit parto of the filter shader and a check box to work on the clamp and RGB multiplier. Also a checkbox to invert the map would be nice.
last but not least, the UV tiling as i am stressing on the corona bug reports, i think the UV tiling really need to be inproved in order to replicate advanced shader like in 3Dsmax, the projection shader is a pain.
Also multi UVw map channel would be the ultimate tool.