I do have 2 of the ISC Mighty Mouse biners, the compactness is nice, and the shape is pretty symmetrical. Loads up nice with a bunch of stuff like both eyes of a hitch cord, a double eye rope wrench tether and a HitchClimber or Phlotich pulley in the middle. That’s about the only time I really like an HMS biner is when it’s more than just a connector for 2 things. The Rock Exotica Pirate is nice too, just a bit bigger. I’m ok with an oval with a pulley and two sewn or spliced eyes, but it’s a little cluttered. If the cord has tied terminations, I’ll use an HMS, but it’s probably not important, so long as it fits and loads nicely and I’m able to still open the gate.
I do need to clean one of the ISCs, the gate is not fully rotating closed and locking on its own, probably a little pitch or something, feels gummy. Likely nothing a little WD40 and a blast from the air compressor won’t fix.
If your shackle is tightened with a tool, it probably ok. I stopped using steel hardware on my aluminum rings and Ds, but I’m probably just babying my saddle. Exception is the steel biner on the HH2. Probably a lousy idea to run an aluminum biner on it. Especially with my dirty ropes. They’ll have a belt sander effect on it lol I gotta hit up the laundromat to wash ropes.