This is more or less what Amazon did when they "cheated" their default font for better readability. It is a bolder version of the "regular" Cecilia.
Quite some time ago - I think in the beginning of 2011 but I'm not sure - we had some pictures here. Someone compared a Kindle with another reader with Pearl screen, a Sony, when I remember rightly. With the default font on both devices the Kindle looked much better readable but when he used the very same font on both devices there was no difference to be seen.