First of all, metal followers are not going to chew up your aluminum frame. The follower, if properly fitted to the magazine, will only contact the slide stop, not the frame. (And the round that's in the magazine, of course).
Original Detonics followers were stainless steel, of the "arched" type. (Whether the magazine bottom says Detoinics 45 Auto or Detonics 45 ACP). They were not made by Metalform. The "45 ACP" mags were made by a sheet steel stamping company in the Pacific Northwest. "New Detonics" mags were made by Metalform. (In my opinion, the Metalform feed lips were a little short).
If you are going to use Metalform magazines, I recommend that you use followers with a full length "tail" on them, and cut away the rear of the floor plate to allow that tail to protrude, as the original Detonics mags did. A full tail stabilizes the follower, (i.e. keeps it in line, so to speak), and makes sure that it only contacts the slide stop.
Anticipating that people would ask, "Why does the follower protrude out the bottom of the magazine?", Detonics called it a "Loaded Magazine Indicator".
Like I posted earlier, "It just keeps getting better, doesn't it".