I’d say the hkern is rather important to the rendering of the text and making it look the way the typographer planned, so I personally wouldn’t remove that.

As for glyph-name=”null” — just did a test on 10 random fonts. Half of them didn’t have any null glyphs at all, the others had one or two such glyphs, so it doesn’t look like a lot of space saving to me — the amoung of these glyphs probably depends on the particular font.

But hey, nice article.

P.S. Would be nice if you fixed my surname in your text, which is Saulis, not SaulUs