Elliot45,
From what I have read here, it will take S&W at least 6 weeks to get your gun back to you. Maybe their turn around is better now, I sure hope so.
We have 2 5" Pro's and a CORE. All of them have the Apex FSS kits in them. 2 have the polymer trigger and one has the aluminum trigger. I left the stock trigger return spring in and the trigger pull on them is around 2.5-3 lbs. We use them in competition and are used to lighter trigger pulls. If we wanted to increase the trigger pull, we would put the Apex trigger return spring in. The FSS kit removes almost 90% of the pre travel and as for over travel, what over travel. The trigger breaks nice and crisp. Apex goes on that the FSS kit makes your trigger feel like an 1911 trigger. The husband doubted that, now he goes on and on about how the trigger feels like his old 1911's. lol BTW, I do not like how the M&P's triggers feel physically, they seem thin to me. That is why all my M&P's handguns have had their physical triggers changed.

I do agree that if the website says 4.5 lbs. then the gun should have a trigger pull of that weight. Just keep in mind that it might take them a while to get the gun back to you and you have a 50/50 chance of them saying that there is nothing wrong with the trigger.