The Syrac click/detent adjustable is what I'm going with on my next one. Gas blocks get hot when you run the gun hard, heat attacks loctite, set screws rattle loose.
Heat will never get to Loctite 640, FWIW. Its what I put my sight bases/gas blocks on with when it matters. You can take the screws out after its set... literally.
I have to heat the base/block with a butane torch, use a block of wood and a 3 pound sledge to beat the base back off again....