The Tac will not harm the finish, as long as you are carefull if/when you want to remove it. Use a utility knife (razor blade type) to cut the tac off the stands, then roll the tac off with your fingures. Rubbing alcohol works well to remove the last little bits of the putty.

I've used this on many bookshelf speakers, and it holds so well to the stands that you will actually pick the stand up (even if sand filled) if you pull on the speaker.

Just as a side note, Axiom should consider doing as Paradigm has started with the new Studio and Signature series. The bookshelf speakers have threaded inserts in the four corners so they can be firmly secured to the custom stands.