I would think a 50w fiber fitted with a 300-something-mm lens would be the kitty's butt for depth-of-field issues on small-arc items like med bracelets. And since a galvo fires from a single point and flares outward in all directions, the slightest Z movement is going to shrink or enlarge the bounding box. Close to the center/small engraving can take some Z movement, but if you're engraving near the lens's boundaries, a little Z movement means a lot of mis-alignment at the far edges... You CAN adjust focus for 'out of range' engraving, but everything must be engraved separately. I've found out the hard way that I can't engrave all of something, then refocus to re-engrave out-of-range items, you end up with 2 separate engravings...

And James, during your machining career, in most cases: did you search out work, or did work find you?