> And then if the new users still want to use the old thing you've got a pretty good red flag that you messed it up. Your new UI might be garbage, but there's

> And then if the new users still want to use the old thing you've got a pretty good red flag that you messed it up. Your new UI might be garbage, but there's no red flag here. A new user will likely need to make use of tutorials, troubleshooting, and other help online; most or all of which will be based on your old UI (and possibly coupled with comments like, 'Don't use the new UI, it's trash. Here is how to switch...'). Having been such a new user, I only pick the new UI when forced or when it's clearly better; the former being the more common case. Sure, you can make your official documentation use the correct UI (or design your UI in such a way that the documentation can be agnostic—but then what is this big change that makes lives better?), but unless your documentation is very good, people are still going to need to reference all these other sources.