One device to rule them all?

[flips01]

Hi!
I've been running an iPad with GoodReader for reading and annotating large image based PDFs (A4/letter sized pages, some scanned book pages).
It's working great, but my eyes get a little strained after some hours.
Is the M92 actually responsive enough to handle this use?
(My Kindle DX does not handle zooming/panning quick enough, I think the CPU is too slow.)

But I also am intrigued by the new fronlighted eReaders. Will there be a large version, or only 6"?
I assume the 6" is not good enough for zooming/panning easily through large/scanned PDFs.(?)

As for general reading of ePubs/mobi's, how does the firmware in Onyx devices handle:
1. Notes/annotations/highlights (how do I sync/access them later, on other devices)?
(Do I need to manually keep read status&current location between iOS reading app, Mac OS X and the Onyx device?)
2. Dictionaries? Can I install multiple? Do they work when offline?
3. Text-to-speech. Does it work on both M92 and the frontlit i62HD Firefly? (I find even the Kindle DX' kinda basic TTS to be of great help when reading.)

I love the idea of having open source firmware.

So, in your experience, what is the main difference in usage compared to Kindle eInk devices?
(What's the main benefits? Any drawbacks I should consider?)