Wait for the .45.
Nothing wrong with the .40 S&W, but it's not enough of a step up over the 9 mm to make you forget that you originally wanted the .45.
“At the core of liberalism is the spoiled child – miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosophy of sniveling brats.” — P.J. O’Rourke