I have the same experience. The NVID RUU works, but al others don't. By the way, the NVID also work with only the "old" drivers installed, not dis-allowing USB connection, not starting in bootloader and not killing wmdc.exe.
I don't know for sure, I noticed the RUU Utility version is newer. But when I just switch the nb.nsk file, I get an error, or it crashes just like before. Can it has something to do with the fact that the NVID RUU updates the SPL as well?