Anyone running a Tweecer with speed density?

I am planning on getting a tweecer soon, and was thinking there is no point to switch to Mass air unless the mass air tweecer alows you to change stuff more.

So basicaly what I am asking is, is a mass air tweecer more tuneable than a speed density tweecer? Also if I convert to mass air later do I have to get a new tweecer?

any ideas?

thanks