40 S&W recoils like a 45ACP and worse in light guns
Mine doesn't. It isn't even close. I can't even feel the recoil of it and it is a plastic gun as you call them. Only certain parts are plastic as you know. Weight is only a part of recoil.
I absolutely love my XDm .40. It doesn't have any recoil at all that I can feel. That stuff about the recoil being too hard is pure hogwash. And hurting the gun???? Yeah right. And all those 10mm cannons don't fall apart after being shot 500,000 times. Someone was trying to steer you to a gun they wanted you to buy IMO. There's NOTHING wrong with a .40 caliber gun. Glock, Springfield, Sig, etc., etc. all make decent models. Find one that fits your hand, your wallet and has the features you want. I did and couldn't be happier.
I'd actually love to have a .45 that holds 16+1 rounds but I haven't found one yet. And one of my .45's kicks hard and the other one I can't even feel the recoil even though it's a much lighter gun. The design of the gun has far more to do with the felt recoil than any other factor. For me the axis height has a lot to do with felt recoil. It is probably different for everyone.
Be prepared to work through a few guns to find the perfect gun for you. Most guns will work reasonably well. Mine all do. But I like the features of my .40 a lot even though I have a .45 that has great features. It just doesn't hold 17 rounds. But I carry both guns often depending on various things like how hot it is and what kind of clothes I will be wearing which means I am limited to a certain kind of holster sometimes. I have various holsters too but if I'm wearing shorts and a t-shirt I'll be carrying my .45 because I have a great IWB holster to carry it in and it's a smaller gun than my .40. My oldest carry pistol is a single stack .45 and is heavier than my other carry guns. So I rarely carry it now even though I carried it for a decade. Well I do have a .25 I bought when I was in college. I used to carry it when I went into certain bars where I knew everyone else had some kind of a gun. Yes I know it was a .25 but it was accurate and easy to conceal in a back pocket. The LEO's told people not to go to those bars without a gun because everyone else had one BTW. What can I say, I lived in a wild town.
But forget the myths people conjure up about calibers. That stuff the guy told you can't possibly be true. .40's have the bullet speed to penetrate metal and angled glass (unlike a .45) and they have more knock down power than a 9mm. The choice of ammo means a lot. My SA will shoot very accurately although it isn't as accurate as my Sig P220 or my Taurus PT-145. It definitely isn't as accurate as my S&W 629 but not much is. Out to 30-35 yards it is plenty accurate enough. It's not a 1911 but it weighs a lot less and holds twice as many bullets. Look for the features YOU want. I did.