On 2011-03-14 Mojca Miklavec
xetex: + system fonts are easily accessible - no protrusion, no font expansion
I never tried to use them, but I thought that Han The Thanh [please add the accents] added that to XeTeX semi-recently (http://scripts.sil.org/svn-view/xetex/TRUNK/, the last comment 8 months ago: "merged microtype branch to trunk").
I don't follow xetex development any more, so my information was outdated. Thanks for the correction.
luatex: + protrusion, font expansion, easy access of system fonts, scripting language included, fast with mplib - in general much slower
... depending on whether "in general" includes metapost or not. A speed factor of ten (faster) is nothing unusual for luatex when many metapost graphics come into play.
I totally agree. But Cecil mentioned in another thread: »My document is mostly text.« Even if a few mp graphics are involved luatex is still noticeably slower. Marco