I would buy the 9mm. The 9mm is more than effective enough for personal protection. Use good ammo and a good double tap to the chest and I promise you the bad guy will go down...if the two to the chest don't work...well that's what the last one to the head is for. I have handguns in .380, 9mm, .40, .45, and .357...I can tell you I do not want to be on the receiving end of any of them
. I've had my XD9 service model since 2004 and have never once had any doubt that it would serve me well in a defense situation. That's just me though...if you are honestly not comfortable with anything other than a .45 then I'd say just wait and buy a gun you'll be happy with.
"They're on our right, they're on our left, they're in front of us, they're behind us; they can't get away from us this time."
Chesty Puller, USMC, Chosin Reservoir, Korean War
"You cannot exaggerate about the Marines. They are convinced to the point of arrogance, that they are the most ferocious fighters on earth - and the amusing thing about it is that they are."
- Father Kevin Keaney, 1st MarDiv Chaplain, Korean War