My 300 fades very slightly under the sun. Since the issue seems to have spread across different generations and models of Sony Readers, could it be related to Vcom adjustment? As far as I understand from the
PRS-300 service manual, readers have to be adjusted for each e-ink display during assembly.
From the service manual: Vcom voltage for the display panel varies for each panel. Vcom adjustment is required when replacing a board or panel.
Maybe low Vcom values reduce the 'stickiness' of black ink?
K.