While the TSi1 and the TSi2 both produce a high launch, they differ in terms of the backspin numbers that you can expect with a well-struck drive.
The TSi1 offers a combination of high launch and moderate spin, which should produce the maximum possible carry if your swing speed is less than 90 MPH.
The TSi2 offers a combination of high launch and low spin, which should produce an ideal carry distance for players with a swing speed that ranges from 90 to 110 MPH. Titleist even calls the TSi2 their ‘Distance Bomber’ golf club. Regardless of where on the face you make contact, you should find it easy to hit bombs with the TSi2, provided your swing speed is reasonably fast.
On this point, it is worth mentioning that if your swing speed is high, you will probably find that the TSi1 produces too much backspin to achieve optimal carry distance. This is problematic because it can lead to a trajectory that balloons upwards rather than penetrating forwards.