IE Standard vs Quirks Mode: Pros and Cons?

yes, IE keeps a list of sites that have to use quirks mode to work (black list) this may effect how sites like bing rank your site and even if not its a pain for people as some people will not know to click the quirks button

People would not need to do anything- as I mentioned, you can specify in your html code that the page should be rendered by IE in compatibility mode.

Do you have any reference that quirks mode indeed affects bing SERP position?

Microsoft maintains a list of websites that have been reported to have problems in IE8's standards mode, known as the compatibility view list. When a user enables this list IE8 will render the websites in the list using its compatibility view mode.[63] The list is occasionally updated to add newly reported problematic websites, as well as to remove websites whose owners have requested removal. The Internet Explorer team also tests the websites on the list for compatibility issues and removes those where none are found.[64]

Mabe so, however we are on IE 8 now so what happens when IE9 comes out? after a while your site will become out of date and using compatibility mode will not encourage you to re-code your site to new stands, and when Microsoft do remove it your site will no longer work...