Not too bad, very solid. And you can just Velcro the pad to the back of it. My Cavision shoulder mount still works with it and it all sits on my shoulder fine, hand held not a issue.

How does that viewfinder square up with you eye on that rig?

I squares up just fine I may have to move my head back a half inch or less, or I just scoot back the shoulder pad bracket back just a little. All I need now is a little extension for the hand grips to lower them just a bit, will help with (slight) front weight. By lowering my elbow reach. Other that that it's really pretty comfortable. If I had to go all day I can put a 3 lb weight in the rear bag, and be able to hold the camera with 2 fingers balanced on shoulder. I think it comes in around 18 or 19 lbs fully rigged with audio at that point. To me the heavier(not killer heavy) the camera is, the smoother the moves.

I'm leaning towards getting a hood pro to replace the viewfinder on the EX3. By making it a bit shorter this type of set-up would be just right ... the weight comes in around the right area!

Yep, the base plate is very good, even if I had to pay top dollar because ours is a bottom dollar. Feels much safer connected to the VCT-14 Sony quick release plate.

I'm leaning towards getting a hood pro to replace the viewfinder on the EX3. By making it a bit shorter this type of set-up would be just right ... the weight comes in around the right area!
I really don't think you need the shorter eye piece, I looks a little close but it really fits fine. I think you would miss just being able to flip up the viewfinder whenever you wanted, instead of removing the sock every time and finding a place for it, while you use the open finder for whatever reason.

Jason, looks like a solid and impressive setup. I'm looking at getting the VF gadget bottom bracket as well due to the lame sony bottom plate design. What matte box do you have and how much?

It is the Cavision model. In all they were the least expensive for everything, matte box, follow focus, etc. And does job just fine.
Cavision Matte Box Configurations for Sony EX1 (http://www.cavision.com/matteboxes/configs/EX1.htm)