SharePoint 2010 and Adobe PDF iFilter - Upgrading from iFilter 9 to 11

We have had Adobe PDF iFilter 9 on our SharePoint 2010 for a while and we are wondering if we can upgrade it easily to Adobe PDF iFilter 11 without breaking the indexing of PDF documents and the search?

Can anyone tell me if you have Adobe PDF iFilter 11 on a SharePoint 2010 web app / server? 

Did you upgrade from iFilter 9 to 11? 

Were there any issues? 

What impacts did it have on the indexing and the search?

Thank you