IDPA is intended to "sort of" simulate real-world scenarios (take that loosely).
It's not perfect for real-world training, but it's better than drawing on yourself looking in a mirror.
You can use any pistol you want for the most part, but be aware that holsters must fall into some guidelines or they won't let you shoot.
Basically, your holster must be worn in such a way as to avoid sweeping other people while drawing, it must be a type typically worn for full concealment, it must be fully secure while wearing and drawing, and it must have a rigid opening to facilitate one-handed re-holstering.
They used to have an "approved" holster list, but there are so many holsters that they now just describe "features" that a holster must satisfy and you should be good to go.
I'd recommend a strong side 3:00 or 4:00 IWB like the VersaMaxII or the MaxConV because it is from holsters like that where you can usually make the fastest and most controlled draw.
In order to come away with some "real-world" basic training from the IDPA experience, you should usually shoot with the pistol you intend to carry the most.
Of course, you can enter more than one category and shoot your brains out (figuratively speaking, of course
).
The 1911 is in a class all by itself ("Custom Defensive" which is for 1911's only), and the XD45 would be in the "Enhanced Service Pistol" class.
Wade through this and knock yourself out:
http://www.idpa.com/Documents/IDPARuleBook2005.pdf#search="idpa"
The best thing for you to do is to simply find a local chapter and show up a half hour before they start for the evening. I'm willing to bet that people will fall all over themselves trying to help a newbee get started and giving you all the info you need right there.
Carter
