I've had probelms with Whitepost, they ruined a caliper in a 911 that I had, when they rebuilt it they stripped the bleeder. After telling me thats they way they got it, and I got stuck with a rebuilt caliper that was useless.
I have had good luck with Apple, but have heard others speak to the contrary. Have never heard of Brakecyliner.com.
Side note, sold 911 to restored BE, funner car, but I am partial.