I would appreciate some feedback regarding the use of $(this)[0].defaultValue for determining whether a textbox value has change from the original value e.g.
It seems pretty safe. i just used this fiddle: http://jsfiddle.net/rXsrQ/ and tested it across chrome/firefox 3.6/safari 4/ ie8, they all behave the same.
It is described here: https://developer.mozilla.org/en/DOM/HTMLTextAreaElement and there is no notice about compatibility issues.
It is also described here: http://msdn.microsoft.com/en-us/library/ms533718(v=vs.85).aspx and seems to be compatible with ie 5 and up, so i don't seem why it shouldn't be safe to use.