Interestingly, I came to the S&W forum for the first time looking for exactly this type of conversation. I had the FSS kit installed in my M&P FS by a local gunsmith and initially had a lot of trouble with the trigger not resetting (during live fire only interestingly enough, dry fire and manual racking of the slide was 100% reliable). I emailed Apex, and their CS was outstanding. Quick, knowledgeable, helpful replies - they were great all the way through. They recommended that I take the pistol back to the gunsmith for another look, and that's what I did. Ultimately he said he had to take a little material off of the slide stop to smooth things out and fix the trigger reset issue, and it does seem to have fixed that. However, it turns out that that material came from the little bump on the gen 3 slide stop that I believe helps with a more tactile reset, so my reset is now almost imperceptible. I got back in touch with Apex, and they again were awesome, telling me the same as you. If I could do it all over again I would've liked the option to send my pistol off to Apex to have them do the work, as they clearly are the experts and probably would've tuned things better than my local guy, but I'm getting used to the missing reset. In the real world, especially with rapid fire, I don't notice it anyway.