I have 3 of the m-80s and love them. As you probably already know, the m-880 replaced them. I now own two of the m-880s. The m-880s are very similar to the m-80s with just a few differences.

Here's the scoop when comparing the two cams:

Positives:
-has a built in system for adding a cable lock for security
-has a PIN function for security
-has two flash modes: one just like the m-80, one for longer distance shots which creates a tunnel like flash out to 90'
-plot watcher functions are updated: you schedule specific times for the plot watcher function (ie 4pm-6pm). No need for plot watcher software downloads on computer as you view the plot watcher as still images

Negatives:
-less options for image capture (ie you can set it to take one pic or two or two fast pics)
-strap is not as functional as the old buckle strap on the m-80
-setup is slightly more confusing IMO, but still not as bad as others