I like the idea, but I am a little wary of this for a couple of reasons.
Firstly it will quickly become very irritating if you have unpaired files, e.g. template classes that only exist in a header file. This will result in people wanting an option to suppress this behaviour.
Secondly there is a lot of variation in how people lay out their code files. Some put the two files in the same directory. Some have "project/src/foo.cpp" and "project/include/foo.h". I have seen various different layouts mentioned here over time.
What I do is place the caret at the top of the file (fast and easy ) and then copy the file name from the definition half of the VA wizard bar, and then feed this file name (CTRL-V) into the IDE's new file dialog. A quick and easy way of ensuring the file names match