Recently I learned a valuable lesson while transferring a WordPress site from a development domain to the live domain.
The theme was written using the built in Text Widgets for both the sidebar and footer widget areas containing everything from navigation menus to scrolling sponsor logos. We were taking advantage of all four widget locations in both the sidebar and footer, as you can imagine there was a good amount of HTML/CSS/JS in the individual text widgets.
Once we had finalized the sites and were switching everything over to the live domain when the database updates were finalizing there was a known error that causes the text widgets contents to not be ported to the live domain.
After a significant amount of time searching on Google there were no known solutions to this problem other than being aware of it and saving your text widget contents in a text file doing the domain transfer and then repopulating the content.
Hope this helps save someone some time!