over both shoulders

[Charles Papert]

What is the circumstance that you need both hands free that much of the time? That implies that you would have the camera locked to your body (like the picture shows), which will limit the amount of tilting you can do to the angle of your body. What if you need to tilt straight up or down?

While focusing needs constant attention, adjusting exposure is usually more of a momentary thing and with the Canons, results in a visible shift in the footage, so I would think it would be done in an "off-air" kind of way so it should be OK to let go of the focus knob at that moment. A more useful handheld rig has a center-mounted handle option so that you are holding the camera up from the center of gravity rather than two handgrips. And of course unrestricted tilt.

[Jon Fairhurst]

I don't find the breathing thing too difficult if the chest rig is adjusted to hit the top of the chest. It's good practice to learn to breathe through the diaphragm anyway for singing, public speaking, and exercising.

The two things I like about The Event are that the arms naturally pull the camera back into the chest, and that it's easy to pull the camera just and inch or two forward and go low.

I use two handles. I can rest my wrist on one handle and have access to the follow focus. I do get some momentary roll when I need to let go with one hand though. A center-of-gravity handle would help in this regard.

Another consideration is how to carry the rig and camera from place to place. A top handle can be helpful for low shots, but might also be nice when walking about. At NAB, I carried my rig for two days and often put one of the rods between my fingers. By the end of the first day, I had compressed a nerve, lost strength in the hand, and it took a month to heal. Shooting was fine. It was carrying the darn thing that injured me!

Dave is right. It all comes down to personal preference. By cobbling up some crazy ideas and trying them in the real world, you can find out what works for you before you spend the money on something nice and adjustable.

My aluminum rig still works, but it threatens to rip up auto upholstery, is large, isn't easily adjustable, and would never fit in my under-the-airline-seat backpack. The Redrock Event is much friendlier for traveling.

[Paul Mailath]

I think this may be what you're looking for

Double Shoulder Mount - Handy FilmTools

it makes a lot of sense to me, with weight on the opposite shoulder, you should be able to achieve a really good balance.

I didn't want to buy one to test it out so I got this:

Rod Support (Rail System) with Shoulder Mount for DSLR (eBay item 250844309402 end time 28-Jun-11 02:27:33 AEST) : Cameras Photo

and bought an extra shoulder mount.I was going to build a dual shoulder mount model but I've come up with a simplier design that feels really comfortable - the good thing about these 'kit' designs is you can alter and adjust as you want.

[Jon Fairhurst]

The problem with shoulder-resting rigs for me is that you really need some weight behind you before you get much meaningful contact. A couple years ago I tried a Redrock unit at NAB that had a fair amount of back weight that felt pretty good. I'm not a big fan of adding dead weight though, so I went with the upper-chest rig. It gives solid contact without the weight.

It would be interesting to try a dual, upper chest rig. Rather than resting on the shoulders, it would press into the front of the shoulders. An advantage is that when you move your hands, there would be absolutely no unwanted roll. The dual chest mount would really eliminate left/right sag. That's especially important for relatively inexperienced operators (like me!) I'm getting better lately, but I used to have a tendency to sag to the right...

Anyway, you might try both a shoulder top pad as well as a front pad to see which you prefer - double or single.