You have a lot of different cameras on your list there — with money not so much a factor, I would drop the GL2 and ag-dvc60 off the list.
If you are not sure what you will want to do or just starting out, I would leave HD aside for now. There is so much to do and learn about SD right now, to keep you quite busy for a while.
The XL2 is a great camera for interchangeable lenses, and it has a solid user community. However, I don’t see it much as an event type camera.
You will also hear nothing but great things about the vx2100.
I have the dvx100b and I absolutely love it. The dvx100 has better audio connections and more features like the 24p and other formats, that will enable a great deal of flexiblitiy — but it does cost more, of course. (There is a rebate going on right now, too)
Of course, I am going to be biased towards my camera – but I honestly do not have anything bad to say about the others.
Check out http://dvxuser.com/articles/shoot3/ for a comparison of the dvx100b, the XL2 and the FX1. (Note: it does come from dvxuser.com, so you might expect a little bias there. It really does seem to be objective though).
Shoulder mounting is doable on any of the cameras – e.g– look at http://www.spiderbrace.com for a cheap alternative.
