Good choice with the .40, I love my .357 but my .40 PX4 is really a more practical weapon (similar power, 3 times the capacity, faster reloads, and of course, ammo is much easier to find!).
If you decide you also need a revolver, you can always pick one up later, after the ammo frenzy dies down. But it won't be because you find your .40 lacking, it'll be because revolvers are just irresistibly cool.
Enjoy, and don't forget the range report!