Never underestimate your opponent I'd say. You never know how much technique your opponent possesses.
---------- Post added 2011-10-05 at 04:14 PM ----------
Depends on the strength level they would be on. If it's medium strong then I would put my bet on the short person because he would be more agile and has the same power in punches as the taller person.
If they would be in heavyweight class strength then I would put my bet on the taller person simply because the shorter person would not have enough body mass to get all that muscle power and still be agile.