The newer Readers, I beleive, weigh less than you mention.
You might look at the weights of these three units, in no particular order of importance, as they're all fine Readers:
1) Cybook Gen3
2) Sony PRS-505
3) Kindle
You can change the font size on these units. I own the Sony unit and it has three font sizes. The unit with the MOST variety of font sizes is the Cybook Gen3. I'm sorry, but I can't remember the font-size choices on the Kindle.
I've heard of ybook, but I'm not familiar with it.
You'll find e-Ink Readers EXTREMELY comfortable to read from. If you like to read in the dark, then you might consider the Ebookwise 1150, as it has a backlit screen. The technology is different - and it's an older technology - but this is also a choice to consider.
I hope this helped on some of your questions.
Let us know if you have more questions.
Don