Feel free to doubt. But I'll clarify my opinion.
First off, a lot of the para and 2011 guys load to 1.18 heck even 1.2 and change. These won't fit in the magazine for most guns chambered in .40. Not to mention that all the load data in the manuals is meaningless once you go to those dimensions. Most importantly, when you have someone who shoots one of these rounds causually say I put a 180gr head over 4.8 grains of titegroup and then doesn't give the OAL, you have really bad advice that could cause someone problems as the math is bad going form a safe longer load to shorter SAAMI specs for max OAL.
As for what will work in the M&P, 1.18 will only fit about 3 rounds in the magazine before they hang up from binding. A little over 1.18 and you only get two. Personally, after having 1.133 OAL rounds bind with a little bit of sand in the magazine, I doubt I'd trust 1.175 to feed while running and gunning. The M&P follower can tilt some, and I can just imagine the 15 round mags lozded to 10 might just allow the rounds to tilt some and bind up with those kind of minimal clearances.
Personally, I try to load as long as i can get away with as it is usually better for accuracy provided you don't go too far with it.
Feel free to doubt, share your experiences with what works for you. I'm just one guy and the more people that contribute detailed info, the better idea we will have what will work.
Those 1.175 rounds, how many you load in the magazine at start? What bullets (i'm using precision delta 180gr, which are a kind of funky profile)? Are you doing fast reloads that might jostle stuf inside, or are you casually shooting from the firing line?
Any of that stuff can make a difference in what will fail to function.
