Can you provide a responsiveness speed guarantee for time sensitive applications (i.e. time for a button press to be detected and sent to the RS232 port)?

Detection time depends on touch parameters which are user-adjustable. With the factory settings, touches are recognized in around 20ms. If there are no commands being executed, the corresponding serial response is sent immediately. However, since the screen could be performing some command when the unit is touched, there is no guarantee. The evaluation kit unit has a keyboard demo that is very responsive. However, the ultimate response time is a function of how the unit is used.