Here is my experience with the AIP upgrades for both the G17 and G18C. G17 on the left and G18C on the right:
The G18C was a drop in fit with no modifications required. The G17 was a bit more tricky (for me at least).
First the AIP hammer bearing was slightly larger than the stock as shown below. As such, when i pulled the slide back, I felt a bit more resistance as the bearing was larger to be pulled down. However, Im using a guarder slide which may be sitting lower compared to the stock slide. In the end, I modified a bit off the blow back housing to reduce the resistance to accomodate the larger bearing. Now I can feel little to no resistance when racking the slide back.
The second issue with the AIP G17 upgrade parts was the sear. As shown below, the raised tabs that the trigger disengages and releases the hammer. A close inspection at both parts reveal that the stock sear has a ramp while the AIP counterpart is rounded. This resulted in a harder trigger pull as the trigger stirrup had to negotiate over the rounded edge as opposed to the ramp. This was a easy fix though.
The last issue that was really bizzarre was the fact the the AIP G17 hammer set came with two (2) valve knockers that didn't quite work. I tried installing both of them and they were light striking the magazine valve and the blow back was weak. However, swapping them out with the SD valve knocker worked much better, blowback was more consistent and harder.