I wanted to report after almost one week of heavy using. Well, I really really love it. I have not had any glare problems yet, or let's say I've had the same problems with the 505, which were very seldom and only if the light source is directly in front of the display. Just changing slightly the orientation of the reader solves the problem for me. I use mostly indirect light, no neons or so, but for this use mostly at home or in the car (on those magical moments for him where DH is allowed to drive my car

), so no problem really.
I end up using the dictionary a lot, which makes me realise that I was just lazy before and did not want to go through the hassle, but could have needed it.
The battery does not last as long as in the 505, but I've just had to charge it again yesterday, and it was only down to a half. I think the notes feature uses more power, and I have been using it a lot.
I use a m-edge cover, and that works fine except for the volume button pressure, so I'll cut a tiny piece of the bottom right corner out, probably today. That may also have been a reason for the battery to go down. I cannot for the life of me understand what Sony thinks, delivering the 600 without a cover. It is really not as if the standard cover was that expensive, considering the material they use is crap, so really they could make the effort.
I had some friends over last weekend, she is european and he is chinese, and I made a demo of the 600 since he had heard about it and was thinking of getting one. He was so amazed he wanted to take mine with him home (I had a second one I just sold last night on ebay), the only thing was that he reads often in chinese and I did not know whether that would work out. He is a gadget freak, has had many toys in his hands through the years, and he was very impressed with the 600. I also showed him my 505, which he liked, but not as much as the 600.
I do not care so much for the touchscreen in the normal reading modus, but it makes the dictionary feature so nice. And I do not dislike the touchscreen in the reading modus, it's just as good as the buttons on the 505, but not better.
As a conclusion, I'll definitely keep my 600 and my 505. I'll probably sell my 300, I haven't used it at all last week, and you can get a good price for them in Europe. It is really not much smaller than the 505, so I end up taking the 505 around.