Hello Jeff,

Firstly addressing your question, depending on what has been customized in terms of colors and what not, there may not be an easy way currently to upgrade WL9 to WL10 while retaining all the customizations/designs. I would highly recommend setting up a test environment to test the upgrade.

There are some solutions you can review,

1) If the customer did a lot of customizations in terms of editing the search.aspx, browse.aspx etc, then prior to upgrading, the customer can back those files up. When they upgrade, they can rename the WL10 search.aspx to something like "searchWL10.aspx" and then bring in those backed up files (assuming the file name is the default, ex: search.aspx; browse.aspx, etc). Note however, that the UI and the behaviors will be exactly like WL9 and will not utilize the new content seen in WL10. Also the color scheme will still vary.

2) I would expect you want to utilize the new WL10 content. When upgrading between WL9 to WL10, the elements were changed to accommodate the backend changes done to WL10.  Thus if you have a lot look/feel changes, I would strongly recommend setting up a test environment first. You may use the WLBundler to copy over your custom links and search forms, along with Theme images. There are some limitations which we are currently looking into improving in the next release of WebLink. Such limitations are theme colors and editting search forms.