A friend of mine found a recent posting on the public Lotus Support database talking about what database properties are affected by a design refresh and a design replace. What made this interesting to me was not the details, but the differences. There are some database properties that are not affected by a regular refresh of the design, but they are affected by a replace of a design.

Basics Tab - Settings changed by both refresh and replace

Type (Standard, Library, Personal Journal, etc.)
Web Access - use JavaScript when generating pages
Web Access - Require SSL connection
Web Access - Don't allow URL open
Allow use of stored forms in this database

Basics Tab - Settings changed only by replace

Display images after loading
Allow document locking

Design Tab - Settings changed by both refresh and replace

Options - Do not mark modified documents as unread

Design Tab - Settings changed only by replace

Options - Allow design locking
Options - Mark parent note on reply or forward
Inheritance - all settings, but only if "inherit future design changes" is selected during the replace
Multilingual Options - all settings if the template has the settings enabled (if the template is multilingual)

Launch Tab - Settings changed by both refresh and replace

All options (client/web launch settings, restore as last viewed by user, show "about database" settings)

Advanced Tab - Settings changed by both refresh and replace

Advanced Options - Optimize document table map
Advanced Options - Don't support specialized response hierarchy

Advanced Tab - Settings changed only by replace

Unread Mark Options - Don't maintain unread marks
Unread Mark Options - Replicate unread marks
Advanced Options - Maintain LastAccessed property
Advanced Options - Use LZ1 compression for attachments
Advanced Options - Allow more fields in database
Advanced Options - Allow soft deletions

The "rule of thumb" is that things that change the physical nature of documents or the database (allow soft deletions, unread marks, document/design locking, etc.) require a replace design instead of a refresh design.

Incidentally, the URL where this information can be found is http://www-1.ibm.com/support/docview.wss?rs=899&uid=swg21176010&ca=lsall