Will roof sand grit clog the stainless steel micro-mesh holes?

About 99% of the time the small roof sand grit will not clog the mesh. You can have challenges with inside miters (inside gutter corners) where there is high accumulation of small debris and rainwater that congregate at the bottom of the roof valley. These areas will need to be brushed off from time to time. In the straight runs of gutter, generally speaking, when the rain drops come down, they splash the roof sand grit off. There will always be a little grit there in that front trough, but it cycles off the mesh, over the gutter and onto the ground and is replaced by other grit coming down the roof.