sorry, i almost forgot this thread. but if you still like to test, i attached a small program, that implements the same interfaces the driver uses. you can compile it like this:
Originally Posted by kokoklems
$ gunzip apple-backlight.cpp.gz
$ c++ apple-backlight.cpp -o apple-backlight
where <OPTIONS> contains which interface to test (--nvidia should work) as well as --get or --set <VALUE>.
$ sudo ./apple-backlight <OPTIONS>
also, did you try to use the nvidia_bl driver? please note: installing both drivers is no problem, but mbp_nvidia_bl will not auto-load anymore (which doesn't matter since it doesn't support your machine anyway).