Updating Evo - need to save assets?

I want to update evo from 1.0.5 to 1.0.8. I am follow the instructions here: http://rtfm.modx.com/display/Evo1/Upgrading

But when I get to the part about uploading the new version and overwriting the old contents, I get a failed transfer message for most of the files I upload... is this meant to occur?

That happens a lot when trying to transfer it via FTP, especially all those little files in TinyMCE. It's much better to upload the whole zip archive, then unzip it and move the new files into place directly on the server.

On the few occasions when I did not have that option (you can usually do it from your host's CPanel or Plesk file manager), I uploaded the assets folders separately, and the TinyMCE plugin itself separately. And there were times even then when I just couldn't get TinyMCE to upload, so I left the old version in place and made sure to skip uploading the plugin when running the installer.