I bought one of these and I just never got around to installing it. I already had a little experience with the M1 in boot camp, so I was aware that the evil "M1 Thumb" wasn't as easy to achieve as some have related. So, I had no fear-driven motive to proceed.
So, it sat in the bottom of the parts box, ignored, for a couple of years.
Curiosity finally got the better of me and I swapped the original op-rod latch for the Holbrook device.
Interesting results. It is much
easier to load partial clips, including single rounds. I may not use the aluminum SLED again. With a little practice, I can remain "slung up" and eject the clip with my R thumb, catching the clip in my R hand.
As I don't do "3-gun" or anything that requires absolute speed in reloading, I think it's kind of cool.
Extremely easy to swap back, if I ever get bored with it. Or if I want to see what "M1 Thumb" feels like.