The 5.7x28mm out of a FiveseveN can match .22 WMR ballistics out of a rifle. So, it's a little better. Bullet construction of the 5.7 is probably better for SD.

Still, in real world use, there's probably not a tremendous advantage. So, like Tedwca said, "pretty much a toss up."

The .22WMR will get you more ammo for the money allowing more practice. That could be a deciding factor in real world application.