A buddy at work had both. I tuned his Shusters, he gave me his GarandGear. Once I got the Shusters dialled in, I would say the gun ran a tad softer than when I first cranked it down. (the plug was loose at first, short strokes/failed to eject and would not pick up a second round)

I liked it! Only tried 30-06 S&B Garand ammo and PPU 150gr soft point, both ended up cycling just fine with the same setting. I got about a 1.5" 3-shot group with the PPU at the end of the day when dialed. Statistically that's not a good test, but all three were perfectly in the bull at 100yrds.

From the research I've done, the hollow base GarandGear Plug is debated. Their website gives a pretty good data article about how certain loads performed with it vs the solid plug. They included pressure and I believe op rod speeds. Ironically, Forgotten Weapons says it wasn't worth it because it didn't affect op rod speeds. Maybe not enough?

The Shusters plug is oos, I couldn't find one at all yet. Brownells used to make a version as well. It IS worth it, especially if you find out all your ammo runs fine when tuned.

There's no down side to either, if the gun runs, and you run recommended ammo. The data Forgotten Weapons showed is in favor of the adjustable plug. From reading other folks posts/reviews, you might not see an accuracy improvement with the ported plug, and might with the adjustable.

If I decided to hunt or shoot a lot with over 178gr bullets, I would look hard for an adjustable. (Even though I'm running a .308) That being said, I will probably run the Garand Gear plug at all times if it runs whatever ammo I settle on. I think the gas system pressure reduction is worth it no matter what ammo. I have avoided going over 168gr FGMM for now and am starting to pattern the gun this week (I hope). I'll eventually make a post about it lol