Mapping problem is strange, probably bug or something like that. Corona promise, have own look, but this is early state. I hope the Corona team in future releases do something about these strange settings. Corona is made a good start, exlude / include options for light, sky, hair is supported to some extent etc., the list will surely grow with time. Some of these things are not yet in Vray for C4D, and he is developing for years.
Mapping is bugged, as there are quite a few very major bugs. All of these bugs are tracked in the bug tracker and are usually quickly assigned to the corresponding dev.
If you feel uncomfortable using a software in alpha state - don't use it, wait for the final product.
And of course you have to keep in mind that Vray for C4D is just a "Bridge" to the integrated Vray Core (which is developed by Chaosgroup), so Laublab doesn't have possibility to make changes to the core.
This is where Corona has an advantage: Both, the Rendering core and the Bridge are being developed by the same people. That means that there will be a full feature set in upcoming releases.
Corona in 3Ds Max is pretty well working right now - as the C4D version will do one day... ;)
