If the XDCam EX files were transcoded to Pro Res 422, then the new Media Composer 5 is advertised to be able to read those quicktime files. I haven’t done it personally, but I haven’t heard of any issues other than you will eventually have to transcode to DNxHD if you want to kick out an AAF for audio mixing.
As far as converting the sequence, Automatic Duck is the way to go, but I’m not positive that it will retain the group clips.
Good luck!
Richard Sanchez
North Hollywood, CA
“We are the facilitators of our own creative evolution.” – Bill Hicks