With my 45c TDA with the lever, I ride my thumb over the safety like a 1911 or USP. I found that after 250 rounds or so, the back of the lever would abuse the knuckle of my thumb to bleed. This doesn’t happen on the USP. That’s partly why LEM appeals to me, along with being more striker fired like. I think the increased size of an HK45 FS would probably negate the thumb bleeding issue.