How about a feature where one is able to change the tag?
Instead of having to select the text in the opening tag, change it, select the closing tag, and then change it.... how about the XML plugin make it do it for you.
This is the essence of what I'm thinking:
1. you are in a tag
2. You click "Change Tag" from the XML Plugin menu
3. It prompts you with a simple input box to type in the new tag.
4. It changes the opening and closing tags for you!