Simultaneous browser testing

Just a quick post as I’ve been sitting on this idea for a while and would like some quick feedback from other designers.
As all web designers will tell you, it’s a pain in the proverbial to do any structured testing of sites in multiple browsers, noticing the nuances in each page as they render is a time consuming process.

My idea is to create an application which will allow the same site to be browsed simultaneously in several different browser engines.
Navigating to a page in any of the browser windows will cause the other browser windows to follow the navigation.

Also one browser window can be chosen as the master (everything works here) and have any differences in rendering be automatically highlighted in the other windows.

Each set of browsers can then be tested with or without flash / js etc with an automatic log of the testing process kept to allow exact replays while issues are being addressed.

Please leave comments below.