I have 3-4 different types of motion sensors, and their hardware response speed has never been slow. So my feeling is that the different motion sensor hardware does not matter, because they are fast enough, and the motion sensor does not actually publish the alarm to me anyroad.
The alarm system does matter. In fact, the ST alarm system has reported multiple false motion alarms to me, that were not immediately previously sent by my sensors.
I suggest don't trigger the alarm in ST. Use ST sensors to notify you "quietly" for investigation.
If you are the only one in the house, no wife or children to disturb, then the noisy alarm shouldn't be a problem for you. The forums have lots of advice about unexpected sirens that can't be turned off.