Pilotbob,
Yes, I use the Cybook for reading novels but the DR1000 for anything pdf based (or at least A4 or larger pdf) and technical docs. the DR is also used more because of the markup facility. Generally I use the DR for "Office" reading or newspapers, but the Cybook almost exclusively for novels etc. I just find the Cybook more convenient to hold etc for reading and it works well with Calibre. I do store my travel insurance detalis in pdf format on the Cybook though
for when I'm on vacation.
as a slight aside, what I would like to add to both is a "welcome screen " that has a photo of me and my phone number in case it gets lost, or some equivalent. But as far as I can see, no device lets you do that yet, ie save & display a password protected file.
Otherwise, each device has its pros and cons