There's an interesting discussion on this topic at the Business Valuation Professionals group on LinkedIn (you'll need to register if you're not a member)begun by Kevin Czerak (Kutchins, Robbins & Diamond, Ltd.). He's got a case where a 39% shareholder is trying to acquire the shares of a 14% owner.
One noteworthy response so far from Joshua V. Azran, CPA/CFF, CMA, CFE:
In many circumstances the swing vote premium is simply an offset of the minority discount. Intrinsically, the argument can be made, but this is both difficult to quantify (extremely entity and situationally specific), and the "range" or "rate" can not be so easily defined.