I personally wouldn't recommend the AE method for long projects. I do mostly short form work and use it in those cases for 2 - 3 second shots at most.
Mercalli works as a plug-in within Vegas - you add the plug-in to your event media and away you go. Much nicer as it can be done right from the timeline without leaving the application.
about the pugin: wow... very nice for 720p out of 1080i/24pA! Equally for SD out of 720p. And forget about it for SD out of 1080 for $119... gotta have it! I want to see what the Vegas experience is like... do you have it?