MacEachaidh, consider this: once I've listed the three best screen for a reader (Kobo Touch, Sony PSR-500 (and the new T1) and Kindle), I went for KT exactly for the font things: not considering Kindle (too closed), I've personally tested Sony PSR-500 here in Italy and it did not support Japanese characters (!) while the same reader, in Japan, obviously did not support accented letters (...). So, I chose KT mainly for the font capabilities, after a "remote" test I've asked to a blogger (see
http://atouchofkobo.wordpress.com/2011/08/28/260/).
With KT I am able to install my own fonts (I go with the UniFont, see
http://unifoundry.com/unifont.html, almost exclusively since it supports full Unicode), allowing wife and me to read both in Italian and Japanese (and also English, for me) and even at the same time, in the same page (!) with no issues except, okay, the very minor thing that we cannot read Japanese vertically (as they are used to) but only horizontally... but we can read!