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’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.