I was having some issues using 12mm bolts mentioned on page 41 of the Stealthburner manual. One of my inserts was a little low, but the other was just about perfect. That one accepts the 12mm screw but not with much thread. The other is too far under for the 12mm to bite. I ran into this closed bug which mentions this. I'm not actually saying it's a bug, was more curious if anyone had any thoughts on downsides (other than adding a tiny bit of weight)? It does seem to fit much better using 16mm.