Varying all vertical metrics between masters, works nicely for instances within glyphs, where interpolations are done within Glyphs. Will varying all vertical metrics between masters work for variable fonts, where interpolations are done after export? It would be for an x-height master, where all vertical metrics including x-height, ascender, descender and caps height vary with the x-height. The total glyph space remains the same, so there would be no clipping, but the proportion between x-height, ascender, descender and caps height changes, as you might expect for varying x-heights. The setup works well for display of instances within glyphs. I haven’t tested it for instance export.