I would prefer a BB military or Hammer machine, too.
However, I've seen a very large no. of freaky big, strong guys use the Smith machines for presses, including Dorian Yates and Trevor Smith. They didn't seem too worried about not working their stabilizers as hard.
Conclusion: I can't see that a BB would be orders of magnitude better than a good Smith press, provided the same kind of effort is put into both.
And it does have the added benefit of focusing exclusively on your contraction...balance and stabilization can be a definite plus in performance, but it's not going to make *that* big a difference to a bodybuilder, whose first, second and third orders of business is contraction, contraction, contraction.