I own a PM9 and a PM40:
As you can see they are exactly the same size in all aspects
except that the PM40 is only
.04'' "thicker" if you can even call it that. The PM40 is heavier unloaded and more noticeably when loaded though - you can hand each of them to me with my eyes closed and I can tell which is which by weight.
As far as size compared to the P series well my friend you're in luck. I took some good side by side pics of my PM9 and a CW40 - he CW40 is the exact same size as your P40, so enjoy the comps!
Side by side - note the exact same trigger guard area. Looks like one pistol there, but the slide and grip length variation is seen here:
Difference in length:
Difference in grip height:
Back to back:
I carry the PM9 in a cheapo KNJ nylon pocket holster (I'm at work 10 hours straight) and it goes completely unnoticed in my work cargo pants. I chooe to carry in my front pocket while at work because I'm jumping in and out of cars, and there are three other employees in my shop that are armed. In the face of danger I'd probably already have my hand in my pocket, gripping the pistol ready for a quick draw. Finding/gripping the pistol is the hardest thing about a quick pocket draw for my set-up.
Old Navy loose fit jeans
can conceal with the same pocket holster, but truth be told a quick draw from the pocket is not nearly as possible as it is in a good ISWB holster.
If I'm out in public (or basically anywhere but work) the pistol is either in a cheapo ISWB KNJ holster, or believe it or not in my back right pocket in a cheapo KNJ pocket holster. This aids in a very quick draw for the unexpected.
I am 6' 195lbs. slightly slim build and I wear medium sized T-shirts and "loose fit" jeans but by no means baggy fit. Even gun people looking for a pistol will never see a PM series in an ISWB holster where I carry it - 12:10 position.
I'll be carrying the PM40 instead (the PM9 is actually my wife's) after I've properly broken it in. Again it's the same size but only heavier. It will be much more pocket-able than a P40 for sure. Hopefully the pics better illustrate that.