I completely agree with you but in addition to yours I use:
- Web Developer: in a simple toolbar you can check whatever part of a page and the behaviour of the browser (e.g. enable/disable cache, cookies, images, css, javascript support but also see response headers and validate the sent code)
- Modify Headers: that let you change and add headers to your request so that you can change virtually everything of your call (e.g. to disable the encoding method so that you can read the traces in clear text not (deflated or gzipped))
- Force Content Type: Via regular expression you can force the browser to change the received content type so that it can be viewed. It is very useful in mobile environments since let you convert multipart Content-Type (not managed by Firefox) to a simple text/html Content-Type and let you see the page.
- ReloadEvery: Let you set a reload timeout so that you can refresh a single page every x seconds.
- WMLBrowser: Let Firefox manage and render WML pages.
About WireShark let me say that if you want a real trace there is no firefox add-on that can match. Even for SSL traffic too since WireShark supports SSL decryption (yes, you need the sever private key but it works.) For the how too please read
http://wiki.wireshark.org/SSL
Nevertheless I agree with you that for simple troubleshooting your (a bit ugly) workaround works perfetly and is always ready to use.