If you drop 2 teeth from your front sprocket then front tyre wear will be decreased as the tyre wouldn't be on the ground very long. One tooth off the front would make the gearing more responsive but decrease your top speed slightly. But by reducing the overall circumferance of the sprocket it would cause the chain to wear quicker. You might also have chain to top of the swingarm clearance problems.
If you reduced the rear sprocket by two teeth it would be similar to adding one tooth to the front sprocket ie. make the gearing less responsive but make the engine more economical in fuel consumption.
Whenever I use one of my bikes for sport/touring (R1 or Exup1000) I drop the rear sprocket by 3 to make it worthwhile. The bikes still pull when you give them a handful, they give better fuel consumption & any buzzing that you get through the footpegs/seat/handlebars with standard gearing is moved away from that part of the rev range.
So in answer to your question, I wouldn't have thought that just one tooth would be a noticeable improvement, but -3 would (similar to +1 on the front sprocket).
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