I don't know if this is important to anyone but I'm managed to use Xtrareport in VS 2012 RC (html and client).
I know it's impossible to use the designer so I created all my things in VS2010 and then moved it it to VS2012.
I then attach the report in a server side mail when inserting in "Sent_reports" table.
It worked nice.
Cool stuff. When you say (html and client) not sure what you mean. Added the xtra dlls to html client or server side LS project?
A writeup would be great. Thanks.