I've got a website which for the most part is a portfolio, there is another section of the site
mysite.com/micro-site which ranks extremely well for the chosen term / topic, and brings in lots of traffic, but actually has little to do with the core business. It was really made as a piece of content - in the same way sites like this are: http://chrome.com/campaigns/rollit
For the main site, I use 1 Google Analytics profile and set of tags, and for the micro-site I have a completely different Google Analytics profile and set of tags.
The main reason I've done this is because the traffic stats and insights for the micro-site are essentially just noise. It's nice to have the traffic but they don't help when reading Google Analytics reports, so if they were combined my reports they would be a mess.
Is there any disadvantage / negatives of doing this?