There was thread in the Large-Bore/Small-Bore Rifle/Shotgun forum about polymer AR lowers, and I believe there was some similar caparison drawn. My opinion is the same, polymer is great, IF, the manufacture takes time to use superior polymer materials, and make sure certain aspect of the frame (All slide-to-frame mating surface ) are designed with sufficient tolerances.
I remember when the Glock came out people were saying it would melt if left in a hot car ( swear to G**, a gun dealer told me that) and would never catch on. If it works and is durable, why not? Trouble is, we are so traditionally married to all steel 1911's, that even if it was the best thing since sliced bread there are those who would never accept it. I don't like Poly guns but I carry one because it is light weight, reliable and it works.
Polymer, like other modern materials, can work very well in guns but IMHO will work best in those guns designed to use it. The Glock is certainly capable of standing up very well, longer than many steel guns, but it is designed to use polymer.
Even allowing that the 1911 was way over-engineered, mainly because Browning had no way to measure materiel strength except to build the gun then shoot the heck out of it. So if a part, say, 1/8" thick failed, he just made it 1/2" thick. But all his work was predicated on the use of the best steel available at the time.
Bul, in Israel, has been making polymer 1911's for years, check the Bul M-5 line. I wouldn't be surprised if this Rock River is actually one of their frames. They seem to hold up, though I have no personal experience with them.
I do know there's no price difference in polymer vs. steel in any I've seen for sale. In fact you can get a basic Rock Island 1911 cheaper then any of the Bul models.
Count me in with the guys who'd rather stick with steel. Nothing wrong with the Polymer frames, just tradition.
I won't knock the polymer frame until I try one. I have shot some old military issue 1911s that were absolutely junk. they rattled like a coffecan with a few bolts in the bottom when you drew them and they were less accurate than a homemade slingshot.
.22 TCM, 1911 platform, with a 9MM barrel thrown in . Had to look it up. I've pretty much talked may self out buying a new gun, but this concept might be fun. Ammo is being made in the states and Cheaper Than Dirt is going to carry it. I wonder how accurate it is going to be. Veddy interesting Dr. Watson. It uses a 40 grain .223 size bullet, no reason it can't be reloaded, bottle neck cartridges work in a auto, Hmmm, I wonder, since I don't have a 9MM on a 1911 platform.