That GFS Didot font is very striking! I like the quill-pen look to it, and it has very dramatic diacritics. But for some reason I find a block of Greek text in Gentium plus to be easier to read than the same text in GFS Didot. Maybe the line thickness is a little too variable? I'm not sure exactly, but there are three specific things about GFS Didot that I didn't care for:
1. Using the English keyboard results in illegible letters; they are too compressed. So you can't alternate between Greek and English without changing fonts. Gentium plus has an attractive (and legible) English font, and so you could write a paper entirely in Gentium plus without any problems.
2. The capital Greek letters do not match the style of the lower case letters. The Caps are made with non-tapering straight lines and have serifs. This is true for Gentium plus as well, but is much less noticeable given the "fountain pen" look of that font.
3. The large diacritics sometimes lead to trouble. The perispomenon of οὗ is partially omitted, and the perispomenon joins with the delta in δἶος. edit:
It seems that this problem may be fixed by adjusting other settings in my word processor. At the apagreekkeys.org site I read that
apagreekkeys.org wrote:For legibility of the accents, the APA fonts have characters that extend vertically up and down farther than most fonts. In some cases, tops or bottoms of characters may appear cut off on the computer screen, although they will print completely. If this happens, it is a good idea to adjust the paragraph formatting entry for line spacing. In Microsoft Word, for instance, instead of using the setting "single" use the setting "at least" and make the line high 2 or 3 points greater than the font size you are using. That is, if you are typing in 12-point BosporosU, set the line spacing to at least 14 or 15 points; or if you are typing in 14-point KadmosU, set the line spacing to at least 16 or 17 points.
Unfortunately, I can't seem to restore the obscured perispomenon by tinkering with the settings.
On the other hand, I didn't notice anything funny with the upsilon in Καΰστρου.
One font I like is found in Chad Bochan's "Iliad A - Scanned West 1998 Teubner text". I am not sure what font it is. Looking at the PDF properties I thought it was BosporosU, but there are lunate sigmas in Chad's document and the rho is more solid than the BosporosU seems to be. The only problem with Chad's font is the mismatch between the capital and the lower case letters. The caps are vertical, not tilted, and the uniform width of the strokes and serifs sets them apart stylistically.