Dear allochi,
thank you so much

. You are really kind! And yes it would be very interessting to talk with you about this per skype - however if you dont mind, I would like to delay that to a later day, because I never really used skype (so I would have to create an account, would get used to it), while I have not so much time for the next days cause I have soon an important study-examination... and I will buy my E-Reader most likely not until July/August (so there is a little bit time till then).
Beside of that: Hey we are neighbors, i am from Austria

!
And, oh I think it will be an important feature for me that I will be able to use a bluetooth mouse and bluetooth keyboard with this device... So the circumstance that this will not be possible with the Sony DPT-S1, will make my final decision probably much easier.
@fgdas
Thank you too!