Hard to find any "pros", as Sibelius Scorch (now owned by Avid) is no longer supported in 64bit browsers - with a particular disfunction in Apple's Safari browsers newer than version 5.1.
When it use to work - it was a great way to access print music, transpose, and playback right in the browser.
Avid has totally dropped the ball on this - no 64bit support. This pretty much limits this to older machines/operating systems/browsers.
Come on Avid. There is no excuse for this to still be an issue.
Avid - you need to get in gear. There is absolutely no excuse to be literally YEARS behind in development of this plugin. Please move forward, your reputation is pretty sullied by your inaction on this issue.