I found several references to the playback cutoff issue in this forum, the CDFreaks forum, and as comments to an article on Ask Dave Taylor (link below). I appreciate Tim's tip on splitting files in CloneDVDMobile -- hadn't noticed this feature before.
I had been moving TV episodes (Boston Legal, Shield, etc) to the A700 and these tend to all convert at around 500MB and play fine - - so I hadn't noticed the issue until scanning the Internet today. I just converted The Bourne Identity at the highest quality setting and the .avi file came out at about 1.3GB and duration was indicated as 1 hr 58 mins. When I moved the file to the Archos 700 and checked file info, it also indicated the same approximate filesize and duration. However when you start the video player, it shows the end as 1hr 37 mins. After that the movie just stops and reverts back to the menu. I went back to the original DVD and the 1 hr 37 min mark happened to be in the middle of a chapter so I don't think that caused anything. I then started doing the math on the filesize and the times (1 hr 37 mins divided by 1hr 58 mins) and I am suspicious that the player only sees and stops at the end of the first gigabyte.
I then tried converting TalentedMrRipley which is longer in duration (2 hr 19 min) and set the quality so it would hit right around 1 GB. It actually came out at 954MB and the entire movie played right to the end. I have just now converted it again at the highest quality level setting and the file came out at 1.078GB. Both files say duration is 2 hr 19mins in file info screen on A700 but when I load the latest file in the video player, it shows end time as 2 hrs 13mins - - just cutting off at the end and again suggesting some type of video playback barrier around 1GB . If so, then I think Archos has a firmware bug and will need to address - - everyone is probably going to need to harass them to get them to take a look at it.
In the meantime, I will use Tim's suggested work around on grabbing a portion of the chapters in CloneDVDMobile and converting then grabbing remainder and converting and having two files.