What you mention about choosing the best execution plan, is covered on Gail's article.
And no, it won't give you better performance as it will use a "safe plan".
You might not believe this, and the best thing to do, instead of guessing is to test.
However, as you mention you need NULL values, then my option would be a dynamic query. As most things regarding SQL Server, the best solution would depend on the situation.;-)