Here's my .02
If you want to "play the game" of IDPA, then you're running for times.
If you want to "train for defensive carry", then dress how you do daily, shoot the same gun you carry daily, etc. and forget about the times.
If you really want to train vs game, you have to only use the times as a tool against yourself, NOT in comparison to others.
An example is this past weekend a local gun club had a classifier. Comparing my last classifier to the most recent: I shaved 3 seconds off my total time and improved my "down count" by 12. Meaning, not only did I shoot faster, but i also shot more accurately.
However, compared to another shooter whom I shot with this last weekend. He shot 23 seconds faster than I, however, his "down count" was 40 to my 29. In the "game" of IDPA, he 'won.' But here's the rub: I shoot IDPA with a XDS 3.3" .45 with FMJ Ball ammo, a 7 round magazine, from an IWB holster and open from button down shirt. Which is what I carry and how I dress every single day(except I carry Critical Defense ammo and I do not carry spare mags...but I can't afford 90 rounds of Critical Defense rounds and I have to have spare mags for the classifier) The other guy, he shot a gun that pushed all the limits IDPA puts out, including 'power factor' with his reloads. He's 'playing the game', and I use it as a training tool.
When I want to 'play the game,' I shoot USPSA in Open class running as close to 165 power factor as I can possibly get with my reloads.
2 totally different worlds, IMO