Here is a link to information about what Audacity may be able to achieve. Audacity
How good or bad a result you get depends on how the original track has been recorded or mixed.
I know, after having tried it, that it can be fairly effective. It does not produce horrible distortion of what sound remains. It just removes the "centre" of the stereo (which is where the vocals are often placed).
As for vocals with reverb. I do not see why that should be any different from vocals without. As long as the reverb is located in the centre of the stereo effect, it will be removed with the rest of the vocal.
Of course, anything Pavane has said about copyright and public use still applies.

Quack!
GtD.