+1 for Storyteller. It is beyond fantastic to have my progress seamlessly synced between my ebooks and audiobooks.
I’m paying for BookFusion, to have synced cross-platform reading. It’s expensive, but seems to be one of the few cross-platform synced readers that supports the EPUB Media Overlays from Storyteller.
Have you experienced ghosting with your Boox tablet? I’d like to get one, but I know that ghosting would bother me.
Storyteller can sync your progress between devices, although there’s occasionally a bit of a bug with it (will be fixed soon). I sync between my iPhone and boox.
Once you get all the e-ink settings dialed in to make black text more readable on the color e-ink screen, it’s pretty damned good. I never notice ghosting. It’s not very easy to get the settings dialed in though. If you are purely reading on it get a black and white screen if it’s in stock so you aren’t fiddling with it to get text to really be boldly black instead of grey.
I run Storyteller app on it and have my ebooks & audiobooks synced up perfectly like whispersync but better.