SDM is definitely faster then FA
In fact, one evening two friends of mine brought their gear to do the testing of AF in real life. We did that in low light enviroment, in local pub.
Opposition was:
Canon EOS 1 Mark II with 70-200/2.8 L
Nikon D 80 with 70-200/2.8 VR
and my K 10 D with DA* 50-135/2.8
We tried to change focus between two points, one was about ten feet, the other was about thirty feet from us, with central focus point active.
Conclusion was: they performed the same, and as long as we aimed correct on an contrast point, focus was equally fast, and locked, when we aimed at some dull point without contrast, focus wasn't obtained. And all three performed the same.
Testing was performed by Sports photographer of the year in Croatia, professional for many years, he is using Canon, so I am confident in results. He said that the result varies in ability to pinpoint the contrast point, and that is skill of a photographer. As far as he is concerned, lens and body from Pentax are top notch.
Forgive me for my bad English, if any.