Well mine was contaminated so it makes sense that smoking it worked shit for me and just irritated my lungs (it also caused uncomfortable rises in blood pressure). Anyway, given the dosages involved with this substance, and the fact that I didn't achieve satisfactory results with a meth pipe (it's nasty shit to smoke too, which was half the problem), I'd say attempting to lace a joint with it would not work well.
Converting it to a salt would probably be wisest, but you can take the freebase via other ROAs and it works all right IME. Oh, and I'd check for contamination...maybe try a melting point test like skillet walked me through on the other page of this thread. Well that wouldn't prove that your impurity was completely harmless and inactive or not though I guess so whatevs.
Of course, if you feel the desire to experiment with vaping it, go ahead and be sure to post the results of your investigation.