Saw the American Rifleman article on the new P15 Kel-Tec, and they mention that the metal slide rail assembly bolts to the polymer grip frame, instead of being in the mold when the plastic is injected to bond/mechanically interlock with the polymer as part of the grip frame.
Is the mold cost and molding process that much easier & faster not having to put the frame rails into the mold to make up for the extra cost for the bolts, tapping the holes in the slide rail part and labor to assemble the two parts? Kel-tec has always been about being the least cost option that still works, and I just don't know enough about the molding process, leaving me to wonder about this method of making a pistol.

My P11 from 2003 has 3 plastic pins that hold the grip to the aluminum frame.  They've been doing it for a long time.  It allows them to offer an all-metal version without making 2 different frames in the P15's case.  Would rather have screws than pins, seems like it'd be more secure.  I have broken one frame pin in the past, shooting +P speer a wee bit too much.

A while back I was thinking of using the P15 as a daily carry option, but I never tried shooting one to get an idea of the reliability of function. A metal P15 is something I'd consider, depending on parts availability.